Protection circuit of display module and display module
By setting up a protection circuit with a high-voltage TVS and a low-voltage Zener diode between the connector and the timing controller, the problem of ESD burning the TCON in LCD production line operations is solved, achieving dual protection of the timing controller against electrostatic discharge and voltage short circuit, thus improving the reliability of the display module.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- CHONGQING BOE OPTOELECTRONICS
- Filing Date
- 2025-07-31
- Publication Date
- 2026-07-07
AI Technical Summary
During LCD production line operations and ODM assembly and testing, the functional pins are adjacent to and directly connected to the VLEDIN high-voltage signal, which can easily lead to electrostatic discharge (ESD) that burns out the timing controller (TCON) and reduces the reliability of the display products.
A high-voltage TVS and a low-voltage Zener diode are connected in parallel between the connector and the timing controller to form a diode protection circuit. The transient voltage suppression diode improves the electrostatic discharge protection voltage level, and the Zener diode is used to adjust the input voltage to the safe operating voltage of the timing controller, thus avoiding voltage short circuits and ESD protection.
It effectively prevents the timing controller from being burned out by external ESD and high voltage at an angle, improves the reliability of the protection circuit of the display module, and reduces the failure rate.
Smart Images
Figure CN224472177U_ABST
Abstract
Description
Technical Field
[0001] This application generally relates to the field of protection circuit design, and more particularly to a protection circuit for a display module and the display module itself. Background Technology
[0002] With the continuous development of display technology, the customized functions based on liquid crystal display (LCD) and timing controller (TCON) are gradually increasing. Specifically, the high-performance digital display interface (i.e., eDP interface) of LCD can meet the corresponding requirements by defining the functions of different pins.
[0003] However, in actual LCD production line operations and ODM assembly testing, since the aforementioned functional pins are usually adjacent to the high-voltage DC signal (i.e., the VLEDIN high-voltage signal) that supplies power to the backlight bar and are directly connected to the TCON, it is easy for misalignment to occur when plugging and unplugging the connector, which may cause the functional pins to short-circuit with the VLEDIN high voltage or burn out the TCON due to electrostatic discharge (ESD), thereby reducing the reliability of the display product. Utility Model Content
[0004] In view of the above-mentioned defects or deficiencies in the prior art, it is desirable to provide a protection circuit for a display module and a display module. In the protection circuit of the display module provided in this application, by using a protector disposed between the connector and the timing controller, on the one hand, the electrostatic discharge protection voltage level of the timing controller when receiving control signals can be improved, and on the other hand, the voltage input to the timing controller can be adjusted to the safe operating voltage of the timing controller. Thus, while realizing electrostatic discharge protection for the timing controller, the voltage short circuit problem is avoided, and the reliability of the protection circuit is improved.
[0005] In a first aspect, the present invention provides a protection circuit for a display module, comprising: at least one protector and a timing controller, wherein a first functional pin of a connector in the display module is electrically connected to the input terminal of the protector, and the output terminal of the protector is electrically connected to the input terminal of the timing controller, and the protector comprises a transient voltage suppression diode and a Zener diode;
[0006] The first functional pin is electrically connected to the transient voltage suppression diode, and the output voltage of the first functional pin is adjusted to a first voltage by the transient voltage suppression diode, wherein the first voltage is less than or equal to the electrostatic discharge protection voltage of the timing controller;
[0007] The first functional pin and the transient voltage suppression diode are electrically connected to the Zener diode, and the Zener diode is used to adjust the input voltage of the Zener diode to the safe operating voltage of the timing controller. The input voltage of the Zener diode includes the output voltage of the first functional pin and / or the first voltage output by the transient voltage suppression diode.
[0008] In one possible implementation, the protector further includes a first current-limiting resistor, which is electrically connected to the input terminals of the transient voltage suppressor diode and the Zener diode, respectively.
[0009] In one possible implementation, the second functional pin of the connector in the display module is electrically connected to the backlight of the display module, and the distance between the second functional pin and the first functional pin is less than a second preset threshold.
[0010] In one possible implementation, the first functional pin is positioned on both sides of the second functional pin.
[0011] In one possible implementation, a fuse is provided between the backlight and the second functional pin.
[0012] In one possible implementation, the first sub-pin of the first functional pin outputs a multi-source data signal to the timing controller through a first protector;
[0013] The first sub-pin is electrically connected to the input terminals of the first transient voltage suppression diode and the first Zener diode of the first protector, respectively, and the output terminals of the first transient voltage suppression diode and the first Zener diode are electrically connected to the input terminal of the timing controller.
[0014] In one possible implementation, the second sub-pin of the first functional pin outputs an overdrive enable signal to the timing controller through a second protector;
[0015] The second sub-pin is electrically connected to the input terminals of the second transient voltage suppression diode and the second Zener diode of the second protector, respectively, and the output terminals of the second transient voltage suppression diode and the second Zener diode are electrically connected to the input terminal of the timing controller.
[0016] In one possible implementation, the third functional pin of the connector in the display module is electrically connected to the input of the timing controller.
[0017] In one possible implementation, a second current-limiting resistor is provided between the third functional pin and the timing controller.
[0018] In a second aspect, a display module is provided, which includes the protection circuit of the display module described in the first aspect.
[0019] The protection circuit and display module provided in this application embodiment, through the protector disposed between the connector and the timing controller, can improve the electrostatic discharge protection voltage level of the timing controller when receiving control signals by using transient voltage suppression diodes, and adjust the voltage input to the timing controller to the safe operating voltage of the timing controller by using Zener diodes, so as to form a two-stage protection circuit that simultaneously avoids high voltage short circuits of the back-end timing controller and provides ESD protection for the timing controller. This solves the problem of the display module going black due to the timing controller being burned out by external ESD and high voltage at an angle, and improves the reliability of the protection circuit.
[0020] Additional aspects and advantages of this invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description
[0021] Other features, objects, and advantages of this application will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:
[0022] Figure 1 This is a schematic diagram of the protection circuit 10 of the display module provided in the embodiment of this application;
[0023] Figure 2 This is a schematic diagram of the first level of protection of the protection circuit 10 of the display module provided in the embodiment of this application;
[0024] Figure 3 This is a schematic diagram of the second level of protection of the protection circuit 10 of the display module provided in the embodiment of this application;
[0025] Figure 4 This is a schematic diagram of the distribution of the first current-limiting resistor 123 provided in an embodiment of this application;
[0026] Figure 5 This is a test schematic diagram of the protection circuit 10 of the display module provided in the embodiment of this application;
[0027] Figure 6 This is a comparative diagram of ESD test results provided in an embodiment of this application;
[0028] In the above image:
[0029] 10 - Protection circuit for display module; 11 - Connector; 111 - Functional pin; 12 - Protector; 121 - Transient voltage suppression diode; 122 - Zener diode; 123 - First current limiting resistor; 13 - Timing controller; 14 - Fuse; TP - Test point. Detailed Implementation
[0030] The present application will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the relevant utility model and not intended to limit the scope of the utility model. Furthermore, it should be noted that, for ease of description, only the parts relevant to the utility model are shown in the accompanying drawings.
[0031] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present application will now be described in detail with reference to the accompanying drawings and embodiments. Furthermore, the term "and / or" in this document is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. The terms "first" and "second," etc., in the specification and claims of the embodiments of this application are used to distinguish different objects, not to describe a specific order of objects.
[0032] First, the terminology used in this application will be explained as follows:
[0033] (1) eDP interface (Embedded DisplayPort): is a high-performance digital display interface designed specifically for embedded devices. Its features include short cables and fixed connections.
[0034] (2) Transient Voltage Suppressors (TVS): These are high-efficiency protection devices in the form of diodes, typically used to prevent damage to downstream circuits caused by instantaneous voltage surges at the port.
[0035] Correspondingly, the high-voltage TVS in this application is a circuit protection device designed specifically for high-voltage applications. It can respond to transient overvoltages (such as lightning strikes, surges, electrostatic discharges, etc.) within nanoseconds and clamp the voltage within a safe range, thereby protecting downstream circuits from damage.
[0036] (3) I2C (Inter-Integrated Circuit) interface: a synchronous, serial, half-duplex communication bus protocol used to connect low-speed peripherals;
[0037] (4) Logo_EN interface: In this application, the CNT's Logo_EN interface is only used as an enable signal for the logo display function of the display module when it is powered on; high / low input level corresponds to enable or disable;
[0038] (5) OD (Over Drive): is an overdrive function of a display module, used to improve the response time of the display, reduce screen delay and ghosting, and improve dynamic clarity. In this application, the OD_EN interface of CNT is only used as the enable signal for this function; input high / low level corresponds to enable or disable.
[0039] Wherein, OD_ENIN=OD_EN, which is the OD function enable signal, and high / low level inputs correspond to enable or disable respectively;
[0040] (6) Multi-Source Data (MSDA): Commonly found on I2C buses or data lines shared by multiple devices;
[0041] (7) Direct contact discharge: The metal electrodes of the test gun directly touch the conductive parts of the device under test (DUT) (such as the metal casing, interface pins).
[0042] (8) Air discharge: The test gun is brought close to the DUT (without direct contact) and discharge is generated through air breakdown;
[0043] (9) VRWM (Reverse Working Voltage) of TVS diode: refers to the highest reverse voltage that a TVS diode can withstand without conducting under normal operating conditions.
[0044] (10) Dynamic Display Switching (DDS): mainly used for dynamic switching between discrete graphics card (dGPU) and integrated graphics card (iGPU) in laptops to improve game performance and reduce latency.
[0045] In existing technologies, LCD 40-pin eDP interfaces typically use pins 34, 35, and 40 to define related functions. For example, the interface may include an Esport I2C interface, a Logo_EN interface, or an OD interface. However, these functional pins are adjacent to the backlight VLEDIN high-voltage signal (e.g., the VLEDIN high-voltage signal pins are pins 36-39) and directly connected to the TCON. Therefore, during LCD production line operations and ODM assembly testing, due to human error, it is easy for the connector to be inserted at an angle, causing a short circuit with the VLEDIN high-voltage signal or ESD to enter and burn out the TCON. This results in a customer return defect rate as high as 50% (e.g., short circuits due to angled insertion of the DDSI2C signal high-voltage signal and ESD entering the TCON account for 50.9% of the total).
[0046] To address the high customer return rate of the aforementioned display products, the current approach is to use a low-voltage Zener diode to protect against the high voltage VLEDIN (i.e., a low-voltage Zener diode is placed between the TCON signal terminal and the ground terminal) to avoid short circuits of the high voltage VLEDIN. However, this protection method cannot provide ESD protection, and the low-voltage Zener diode itself does not have sufficient ESD resistance, posing a risk of being burned out by ESD, thus increasing the risk to module reliability.
[0047] Based on this, this application provides a protection circuit for a display module. The protection circuit of the display module consists of a high-voltage TVS and a low-voltage Zener diode connected in parallel to form a diode protection circuit, which is connected in series between the connector and the protected signal of the TCON. This allows for simultaneous protection against high-voltage short circuits and ESD for the back-end TCON. Furthermore, the protection circuit of the display module itself is not at risk of damage, thus ensuring its reliability.
[0048] In one possible implementation, Figure 1 This is a schematic diagram of the protection circuit 10 of the display module provided in the embodiments of this application, as shown below. Figure 1 As shown, the protection circuit 10 of the display module includes at least one protector 12 and a timing controller 13. The first functional pin of the connector 11 in the display module is electrically connected to the input terminal of the protector 12, and the output terminal of the protector 12 is electrically connected to the input terminal of the timing controller 13. The protector includes a transient voltage suppression diode 121 and a Zener diode 122.
[0049] For example, connector 11 is provided with multiple functional pins 111, and different control signals to timing controller 13 can be generated by defining each functional pin 111. That is, connector 11 corresponds to CNT of display module.
[0050] Specifically, connector 11 is used to output different control signals through different function pins 111, and transmit the control signals corresponding to each function pin 111 to timing controller 13 through protector 12.
[0051] For example, among the multiple function pins 111, the control signal output by the first function pin electrically connected to the input terminal of the protector 12 includes at least a multi-source data signal (MSDA signal) and an overdrive enable signal (OD_ENIN signal). That is, the module CNT inputs the MSDA signal and the OD_ENIN signal from the first function pin to the signal input terminal of the timing controller.
[0052] Correspondingly, when connector 11 includes a 40-pin eDP interface, pin 34 can be defined as an I2C interface to output the MSDA signal; pin 40 can be defined as an OD interface to output the OD_ENIN signal.
[0053] It should be noted that the control signals transmitted to the timing controller 13 include, but are not limited to, the control signals generated by the I2C interface and the OD interface mentioned above. The interfaces can be adjusted accordingly according to the signal requirements, and this application does not impose any specific restrictions on them.
[0054] In one possible implementation, the input terminal of the protector 12 is connected to any functional pin 111, and the output terminal of the protector 12 is connected to the input terminal of the timing controller 13. That is, the protector 12 is connected in series between the connector 11 and the timing controller 13. The protector 12 includes a transient voltage suppressor diode 121 (i.e., a high-voltage TVS) and a Zener diode 122 connected in parallel.
[0055] For example, the first sub-pin of the first functional pin 111 outputs a multi-source data signal (i.e., MSDA signal) to the timing controller 13 through the first protector. The first sub-pin is electrically connected to the input terminals of the first transient voltage suppression diode and the first Zener diode of the first protector, respectively. The output terminals of the first transient voltage suppression diode and the first Zener diode are electrically connected to the input terminals of the timing controller 13, respectively. The second sub-pin of the first functional pin 111 outputs an overdrive enable signal (i.e., OD_ENIN signal) to the timing controller 13 through the second protector. The second sub-pin is electrically connected to the input terminals of the second transient voltage suppression diode and the second Zener diode of the second protector, respectively. The output terminals of the second transient voltage suppression diode and the second Zener diode are electrically connected to the input terminals of the timing controller 13, respectively.
[0056] Correspondingly, refer to Figure 1In the protection design of the MSDA signal output, the first sub-pin is pin34, the first transient voltage suppression diode 121 is D102, and the first Zener diode 122 is D104; in the protection design of the OD_ENIN signal output, the second sub-pin is pin40, the second transient voltage suppression diode 121 is D101, and the second Zener diode 122 is D103.
[0057] Specifically, when the voltage input to the protector 12 exceeds a first preset threshold, the protector 12 uses a transient voltage suppression diode 121 to adjust the input voltage to a first voltage and inputs the first voltage to a Zener diode 122. The first voltage is less than or equal to the electrostatic discharge (ESD) protection voltage of the timing controller. The first preset threshold is, for example, the maximum ESD protection voltage of the timing controller 13.
[0058] Based on this, the transient voltage suppressor diode 121 can provide the downstream Zener diode 122 and the timing controller 13 with ESD protection that meets the electrostatic discharge requirements, and the transient voltage suppressor diode 121 will not be damaged by the continuous high voltage VLEDIN due to its own characteristics.
[0059] Specifically, the protector 12 is also used to adjust the input voltage of the Zener diode 122 to the safe operating voltage of the timing controller 13 using the Zener diode 122. The input voltage of the Zener diode 122 includes the input voltage of the protector 12 and / or the first voltage.
[0060] For example, refer to Figure 1 The protector 12 also includes a first current-limiting resistor 123, which is disposed between the input terminals of the transient voltage suppression diode 121 and the Zener diode 122.
[0061] Specifically, the first current-limiting resistor 123 is used to adjust the input current of the Zener diode 122 to achieve current-limiting protection for the Zener diode 122.
[0062] Based on this, the VLEDIN continuous high voltage can be limited within the safe operating voltage range of the timing controller 13 by the cooperation of the Zener diode 122 and the first current limiting resistor 123. At the same time, the instantaneous high voltage corresponding to ESD after being limited by the transient voltage suppression diode 121 can also be limited to a lower safe voltage by the Zener diode 122, so as to avoid the situation where the excessive first voltage (i.e., electrostatic discharge protection voltage) generated by the transient voltage suppression diode 121 damages the downstream protected circuit.
[0063] Correspondingly, refer to Figure 1In the protection design of the MSDA signal output, the first current limiting resistor 123 is R104; in the protection design of the OD_ENIN signal output, the first current limiting resistor 123 is R124.
[0064] The protection circuit 10 of the display module provided in this application embodiment can be extended to the protection structure of the transient voltage suppression diode 121, the Zener diode 122 and the first current limiting resistor 123 according to different protection signal requirements, so as to achieve the protection effect on different input signals of the timing controller 13.
[0065] In another embodiment of this application, the first level of protection of the protection circuit 10 of the display module is also specifically described.
[0066] For example, refer to Figure 1 The protection circuit 10 of the display module is also equipped with a backlight VLEDIN. The second functional pin of the connector 11 in the display module is electrically connected to the backlight VLEDIN of the display module, and the LCD VLEDIN usually supports 5V~21V input.
[0067] Wherein, the distance between the second functional pin and the first functional pin is less than a second preset threshold; for example, the second functional pin is arranged adjacent to the first functional pin. Correspondingly, refer to Figure 1 The first function pin (including MSDA and OD_ENIN) is located on both sides of the second function pin (backlight VLEDIN).
[0068] Specifically, when connector 11 includes a 40-pin eDP interface, pins 36 to 39 can be defined as VLEDIN. Corresponding to this pin design, the MSDA signal and OD_ENIN signal are connected adjacent to the VLEDIN high-voltage signal.
[0069] Based on this, in order to prevent the ESD protection design of the display module's protection circuit 10 from being burned by the VLEDIN oblique insertion, the first level of protection of the display module's protection circuit 10 provided in this embodiment improves the ESD protection voltage level when the timing controller 13 receives the control signal output from the functional pin 111 of the connector 11 by using the transient voltage suppression diode 121, while avoiding being burned by the high voltage VLEDIN oblique insertion.
[0070] For example, refer to Figure 1 A fuse 14 is provided between the backlight end and pin 111 to provide overcurrent protection through the fuse's melting mechanism. The fuse 14 corresponds to... Figure 1 F1 in the game.
[0071] For example, Figure 2This is a schematic diagram of the first level of protection of the protection circuit 10 of the display module provided in the embodiments of this application, as shown below. Figure 2 As shown, the transient voltage suppressor diode 121, based on its high response speed and high surge absorption characteristics, can change its high impedance to low impedance in a very short time when subjected to instantaneous high voltage energy impact at its input and output terminals, so as to limit the voltage across its terminals to a predetermined voltage value Vc while absorbing the instantaneous ESD large current.
[0072] Specifically, taking the ESD protection level of the timing controller 13 unit as less than or equal to ±15kV as an example, Table 1 is a schematic table of parameter information of a TVS tube provided in the embodiments of this application, such as... Figure 1 As shown, the TVS tube can provide ESD protection of greater than or equal to ±30kV for air discharge or direct contact discharge, which is much higher than the ESD protection level of the timing controller 13.
[0073] Table 1a Parameter table of TVS tubes provided in the embodiments of this application
[0074]
[0075] Table 1b Parameter table of TVS tubes provided in the embodiments of this application
[0076]
[0077] For example, the reverse operating voltage Vrwm of the transient voltage suppressor diode 121 is higher than the maximum value of the backlight to avoid the high voltage VLEDIN burning out the transient voltage suppressor diode 121. The reverse operating voltage Vrwm can be greater than or equal to 24V.
[0078] It should be noted that the value of the reverse working voltage Vrwm can be adjusted according to the VLEDIN voltage range. Taking the TVS diode as an example, when the backlight VLEDIN is 12V, the reverse working voltage Vrwm of the transient voltage suppressor diode can be 14V.
[0079] In another embodiment of this application, a second level of protection for the protection circuit 10 of the display module is also specifically described.
[0080] Because TVS diodes with high withstand voltage and high ESD protection characteristics typically have a high limiting voltage Vc (e.g., Vc is 29V), the ESD voltage output after the first-stage protection in the previous embodiment (i.e., the instantaneous voltage of 29V) is still higher than the normal operating voltage of the timing controller 13, which can easily lead to the burning out of the timing controller 13. Based on this, this embodiment provides a second-stage protection circuit design including a low-voltage Zener diode 122. The power dissipation of this Zener diode 122 can be greater than or equal to 200mW.
[0081] For example, Figure 3 This is a schematic diagram of the second-level protection of the protection circuit 10 of the display module provided in this application embodiment, as shown below. Figure 3 As shown, when the input voltage of Zener diode 122 is the same as the input voltage of protector 12, Zener diode 122 can adjust the input voltage to the safe operating voltage of timing controller 13, so as to limit the large voltage VLEDIN that enters due to the slant short circuit to the safe voltage when the back-end TCON is working.
[0082] For example, such as Figure 3 As shown, when the input voltage of the Zener diode 122 is the first voltage (i.e., the electrostatic protection voltage adjusted by the transient voltage suppression diode 121), the ESD voltage at the front end, which is limited to Vc by the transient voltage suppression diode 121, can be further limited to the safe voltage range of the timing controller 13, so as to make up for the defect that the transient voltage suppression diode 121 cannot clamp the ESD voltage to the safe voltage in the first-level protection.
[0083] For example, based on its reverse breakdown characteristics, the Zener diode 122 can instantly enter the breakdown region when the high voltage VLEDIN (i.e., the angled high voltage) or the first voltage (i.e., the limiting voltage Vc of the transient voltage suppressor diode 121) reaches the Zener diode 122 through the first-stage protection circuit, so as to discharge the current to ground and limit the voltage to the safe voltage Vz (i.e., the safe operating voltage of the timing controller 13), thereby achieving the purpose of protecting the back-end timing controller 13.
[0084] For example, the safe operating voltage of the timing controller 13 (i.e., the limiting voltage adjusted by the Zener diode 122) is less than the withstand voltage of the first functional pin.
[0085] Specifically, the limiting voltage Vz of the Zener diode 122 can be less than or equal to the maximum withstand voltage of the timing controller 13 when receiving the control signal. For example, when the maximum withstand voltage of the timing controller 13 when receiving the control signal is 3.6V (i.e., the withstand voltage of the TCONI2C MSDA pin is 3.6V max), a Zener diode with a limiting voltage Vz of standard value 3.3V (i.e., 3.3V typ), a maximum value of 3.5V (i.e., 3.5V max), and a power dissipation of 300mW can be used as the Zener diode 122.
[0086] It should be noted that Zener diodes 122 that can provide different limiting voltage Vz values can be selected according to the actual needs of the pin to be protected. For example, when the maximum withstand voltage of the OD pin is 5V, Zener diodes 122 with a limiting voltage Vz of standard value 4.3V (i.e., 4.3V typ) and maximum value of 4.6V (i.e., 4.6V max) can be used.
[0087] For example, the maximum breakdown current of the Zener diode 122 can be the ratio of the power dissipation of the Zener diode 122 to the safe operating voltage, which can be expressed by the following formula:
[0088] Ipp=Pd / Vz
[0089] Where Ipp represents the maximum breakdown current of Zener diode 122, Pd represents the power dissipation of Zener diode 122, and Vz represents the limiting voltage of Zener diode 122; for example, when the power dissipation Pd of Zener diode 122 is 300mW and the limiting voltage Vz of Zener diode 122 is 3.5V, the maximum breakdown current of Zener diode 122 is Ipp = 300mW / 3.5V = 85.7mA.
[0090] In another embodiment of this application, a current-limiting protection device for the Zener diode 122 is also specifically described.
[0091] In the previous embodiment, when the Zener diode 122 limits the input voltage to the safe operating voltage of the timing controller 13, its operating current should also be set below the safe current Ipp to ensure that it is not burned out.
[0092] Based on this, this embodiment adds a series current-limiting resistor RL between the first level of protection and the second level of protection to limit the maximum current of the link, thereby ensuring the safe operation of the Zener diode 122.
[0093] For example, Figure 4 This is a schematic diagram of the distribution of the first current-limiting resistor 123 provided in an embodiment of this application, as shown below. Figure 4As shown, a first current-limiting resistor 123 can be connected in series between the input terminals of the transient voltage suppression diode 121 and the Zener diode 122 to prevent the Zener diode 122 from burning out due to overcurrent.
[0094] Specifically, the resistance value of the first current-limiting resistor 123 can be determined based on the first voltage, the safe operating voltage, and the maximum breakdown current of the Zener diode 122.
[0095] Correspondingly, the voltage difference between the first voltage and the safe operating voltage can be determined first, and then the resistance value of the first current-limiting resistor 123 can be determined based on the ratio of the voltage difference to the maximum breakdown current of the Zener diode 122. Specifically, this can be expressed by the following formula:
[0096] RL = ΔV / Ipp, ΔV = Vc - Vz
[0097] Wherein, RL represents the resistance value of the first current-limiting resistor 123, and ΔV represents the voltage difference.
[0098] For example, when the first voltage Vc is 29V, the safe operating voltage Vz is 3.3V, and the maximum breakdown current Ipp of the Zener diode 122 is 85.7mA, the resistance of the first current limiting resistor 123 is RL = (29V - 3.3V) / 85.7mA = 300Ω, so as to limit the protection link current to within 85.7mA, thereby realizing the voltage regulation function of the back-end Zener diode 122.
[0099] In another embodiment of this application, other component distributions of the protection circuit 10 for the display module are also provided.
[0100] For example, the third function pin of connector 11 in the display module is electrically connected to the input terminal of timing controller 13, that is, the third function pin can directly input control signals into timing controller 13.
[0101] Secondly, exemplarily, refer to Figure 1 A second current-limiting resistor R105 is provided between the third function pin 35 and the timing controller 13.
[0102] In another embodiment of this application, a display module 20 is also provided, which includes the protection circuit 10 of the display module in the above embodiment.
[0103] The display module 20 in this application, through the protection circuit 10 that can simultaneously prevent TCON ESD and high voltage burn-out of the display module, increases the reliability of the display module 20 and greatly reduces the problem of defective burn-out in module factory production and customer mass production.
[0104] In another embodiment of this application, a method for testing the protection capability of the protection circuit 10 of a display module is also provided.
[0105] In this embodiment of the application, the protected signal in the protection circuit 10 of the display module that is adjacent to the high voltage signal by 1~2 pins may include I2C BUS (MSDA / MSCL), Logo_EN, I2C_EN, OD_EN, Esport, etc.; the source of the high voltage signal in the protection circuit 10 of the display module may include VLEDIN, VDDIN, etc.
[0106] For example, Figure 5 This is a test schematic diagram of the protection circuit 10 of the display module provided in the embodiment of this application, as shown below. Figure 5 As shown, the protected signal in the protection circuit 10 of the display module is the TCON I2C bus (MSDA); the source of the large voltage is VLEDIN (DC power supply external voltage simulation) of 5~21V; the source of ESD is the QA ESD generator that emits ±15kV~±30kV, which includes Air mode and Contact mode (the settable limit voltage is ±30kV).
[0107] refer to Figure 5 The protection circuit 10 based on the display module includes the TVS D102, current limiting resistor R104 (300Ω) and Zener diode D104 provided in the above embodiment. The test method includes high voltage slant insertion protection test and ESD protection test.
[0108] Specifically, for the high-voltage oblique insertion protection test, an LCD panel was selected, with each individual LED lit. A DC power supply of 2~21V was applied from the test point TP, and the voltage at the back end of resistor R104 was measured at 2V / step. For the ESD protection test, three LCD panels with different TCONs were selected, with each individual LED lit. An ESD generator was used to perform air mode and contact mode ESD discharge tests from the test point TP, with a test range of ±15kV~±30kV. Each voltage was measured 20 times (air / contact) at ±5kV / step.
[0109] Correspondingly, the criterion for high-voltage angled insertion protection test is that the voltage behind R104 is within the Zener diode specification, and the characteristics of each component are normal; the criterion for ESD protection test is that after each voltage level of ESD is applied by the ESD gun, there is no abnormal display on the screen, and after 10 normal I2C programming cycles, the characteristics of each component are normal. For example, Table 2 is a schematic table of high-voltage angled insertion simulation test results provided in the embodiments of this application. As shown in Table 2, different clamping voltages of the measuring resistor R104 can be obtained for every 2V / step.
[0110] In one example, taking a 16.0 WQ 240Hz panel as an example, with an external voltage of 2~21V, a R104 back-end clamping voltage of 3.446V max, and a Zener diode of 3.5V max spec, the characteristics of each component were checked and found to be normal.
[0111] Table 2. Schematic diagram of high-voltage oblique insertion simulation test results
[0112]
[0113] In another example, Figure 6 This is a comparative diagram of ESD test results provided in an embodiment of this application, such as... Figure 6 As shown in (a), three different TCON gaming panels were selected, and ESD tests without protection circuitry (i.e., without ESD protection circuitry) were performed at the TP test points in the figure. Only ANX2176 and NT71877 passed the ±15kV@air mode test, while the others failed. Based on this, it can be analyzed that the failed panels were all due to a short circuit in the TCON's internal VDD or a burnt-out I2C module that could not connect, resulting in a black screen with no display and no recovery. Figure 6 As shown in (b), the same panel was selected, and the ESD test of the protected circuit (i.e., the ESD protection circuit component) was performed from the TP test point in the figure. All three panels can pass the ±30kV air mode & contact mode ESD test. After the test, they can all be displayed normally. At the same time, the characteristics of each device are normal, and they can all pass the I2C repeated programming 10 times.
[0114] The above description is merely a preferred embodiment of this application and an explanation of the technical principles employed. Those skilled in the art should understand that the scope of disclosure in this application is not limited to technical solutions formed by specific combinations of the above-described technical features, but should also cover other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the foregoing disclosed concept. For example, technical solutions formed by substituting the above features with (but not limited to) technical features with similar functions disclosed in this application.
Claims
1. A protection circuit for a display module, characterized in that, include: At least one protector and a timing controller, wherein the first functional pin of the connector in the display module is electrically connected to the input terminal of the protector, and the output terminal of the protector is electrically connected to the input terminal of the timing controller, and the protector includes a transient voltage suppression diode and a Zener diode; The first functional pin is electrically connected to the transient voltage suppression diode, and the output voltage of the first functional pin is adjusted to a first voltage by the transient voltage suppression diode, wherein the first voltage is less than or equal to the electrostatic discharge protection voltage of the timing controller; The first functional pin and the transient voltage suppression diode are electrically connected to the Zener diode, and the Zener diode is used to adjust the input voltage of the Zener diode to the safe operating voltage of the timing controller. The input voltage of the Zener diode includes the output voltage of the first functional pin and / or the first voltage output by the transient voltage suppression diode.
2. The protection circuit for the display module according to claim 1, characterized in that, The protector also includes a first current-limiting resistor, which is electrically connected to the input terminals of the transient voltage suppression diode and the Zener diode, respectively.
3. The protection circuit for the display module according to claim 1, characterized in that, The second functional pin of the connector in the display module is electrically connected to the backlight of the display module, and the distance between the second functional pin and the first functional pin is less than a second preset threshold.
4. The protection circuit for the display module according to claim 3, characterized in that, The first functional pin is located on both sides of the second functional pin.
5. The protection circuit for the display module according to claim 3, characterized in that, A fuse is provided between the backlight and the second functional pin.
6. The protection circuit for the display module according to claim 1, characterized in that, The first sub-pin of the first functional pin outputs a multi-source data signal to the timing controller through the first protector; The first sub-pin is electrically connected to the input terminals of the first transient voltage suppression diode and the first Zener diode of the first protector, respectively, and the output terminals of the first transient voltage suppression diode and the first Zener diode are electrically connected to the input terminal of the timing controller.
7. The protection circuit for the display module according to claim 1, characterized in that, The second sub-pin of the first functional pin outputs an overdrive enable signal to the timing controller through the second protector; The second sub-pin is electrically connected to the input terminals of the second transient voltage suppression diode and the second Zener diode of the second protector, respectively, and the output terminals of the second transient voltage suppression diode and the second Zener diode are electrically connected to the input terminal of the timing controller.
8. The protection circuit for the display module according to claim 1, characterized in that, The third functional pin of the connector in the display module is electrically connected to the input terminal of the timing controller.
9. The protection circuit for the display module according to claim 8, characterized in that, A second current-limiting resistor is provided between the third functional pin and the timing controller.
10. A display module, characterized in that, The protective circuit for the display module as described in any one of claims 1-9 is included.