WO2020177399A1

WO2020177399A1 - Display apparatus and overvoltage detection method

Info

Publication number: WO2020177399A1
Application number: PCT/CN2019/120098
Authority: WO
Inventors: 迟洪波
Original assignee: 青岛海信电器股份有限公司
Priority date: 2019-03-07
Filing date: 2019-11-22
Publication date: 2020-09-10
Also published as: CN109727564A

Abstract

Provided are a display apparatus and an overvoltage detection method. The display apparatus comprises a circuit board. The circuit board comprises: a feedback circuit (242), an overvoltage protection circuit (244) and a functional circuit, wherein the feedback circuit (242) is used for determining the voltage of a feedback end according to an output voltage of an output end of the functional circuit; the overvoltage protection circuit (244) is used for indicating the output voltage of the output end to an overvoltage detection end of the functional circuit through an overvoltage indication end; and the functional circuit is used for controlling, when the overvoltage detection end detects that the voltage of the output end of the functional circuit is greater than a pre-set working voltage after a pre-set time period since the display apparatus entered a working state, the functional circuit such that same stops working. The overvoltage protection circuit (244) and the functional circuit can play the effect of overvoltage protection when the feedback circuit (242) is abnormal.

Description

Display device and overvoltage detection method

This patent application claims the priority of the Chinese patent application filed on March 07, 2019 with the application number 201910171476.4 and the invention title "Display Device and Overvoltage Detection Method". The full text of this application is incorporated into this by reference. Applying.

Technical field

This application relates to the field of electronic equipment, such as a display device and an overvoltage detection method.

Background technique

With the development of technology and the increasing demands of users, there are more and more electrical appliances in users' homes, providing users with all-round convenience and entertainment. Household appliances usually include a power module, and the power module is used to convert AC power provided by the grid into DC power. In the process of power conversion, current harmonics will be generated, and the injection of current harmonics into the grid will cause interference to the grid and affect other electrical equipment in the grid. With the wide application of various household appliances, the problem of current harmonic interference to the power grid has become increasingly prominent.

At present, the suppression of current harmonic interference in household appliances usually adopts a method of adding a power factor correction (PFC) circuit to the power supply module. The main function of the PFC circuit is to keep the voltage and current in the same phase, so that the load is similar to resistive, thereby increasing the effective power and reducing current harmonic interference; at the same time, it can also provide a stable DC power signal to electrical equipment. A feedback loop is provided in the power module to provide a stable DC power signal to electrical equipment. The feedback loop is used to feed back the voltage signal output by the power module to the PFC circuit, and the PFC circuit adjusts the voltage signal output by the power module according to the feedback voltage signal to stabilize the voltage signal output by the power module. Among them, the feedback coefficient between the feedback voltage signal and the voltage signal output by the power module depends on the parameter of the device on the feedback loop.

However, when the feedback loop is abnormal, for example, the resistance of the device on the feedback loop changes. For the same voltage signal output by the power module, the voltage signal provided by the abnormal feedback loop to the PFC circuit is the same as the normal feedback loop. The voltage signals provided are different. At this time, the PFC circuit still adjusts the output voltage of the PFC circuit according to the abnormal voltage signal, so that the voltage of the feedback terminal of the PFC circuit stabilizes at the preset reference voltage. Therefore, when the voltage of the feedback terminal of the PFC circuit is consistent with the preset reference voltage under abnormal conditions, the output voltage of the PFC circuit cannot be stabilized at the normal working voltage, and it is very likely to exceed the normal working voltage, and a safety failure may occur.

Summary of the invention

One aspect of the embodiments of the present application provides a display device including a circuit board, the circuit board includes: a feedback circuit, an overvoltage protection circuit, and a functional circuit; wherein,

The output terminal of the functional circuit is respectively connected to the first terminal of the feedback circuit and the first terminal of the overvoltage protection circuit, and the second terminal of the feedback circuit is connected to the feedback terminal of the functional circuit. The second terminal of the overvoltage protection circuit is grounded, and the overvoltage detection terminal of the functional circuit is connected to the overvoltage indication terminal of the overvoltage protection circuit;

The feedback circuit is used to determine the voltage of the feedback terminal according to the output voltage of the output terminal of the functional circuit;

The overvoltage protection circuit is configured to indicate the output voltage of the output terminal to the overvoltage detection terminal of the functional circuit through the overvoltage indication terminal;

The functional circuit is used to adjust the output voltage of the functional circuit so that the voltage of the feedback terminal is consistent with the preset reference voltage; when the voltage of the feedback terminal is consistent with the preset reference voltage, the output of the functional circuit The voltage is the preset working voltage;

The functional circuit is further configured to control the output voltage of the functional circuit to be greater than the preset operating voltage after the overvoltage detection terminal detects that the output voltage of the functional circuit is greater than the preset operating voltage after a preset period of time after the display device enters the working state The functional circuit stops working.

Another aspect of the embodiments of the present application provides an overvoltage detection method, which is applied to a display device, the display device includes a PFC circuit, and the method includes:

Get the status of the display device;

When the display device enters the standby state, stop performing overvoltage protection on the output terminal of the PFC circuit.

Description of the drawings

One or more embodiments are exemplified by the accompanying drawings. These exemplified descriptions and drawings do not constitute a limitation on the embodiments. Elements with the same reference numbers in the drawings are shown as similar elements. The drawings do not constitute a scale limitation, and among them:

FIG. 1 is a schematic structural diagram of a display device provided in Embodiment 1 of this application;

FIG. 2 is a schematic structural diagram of a power supply assembly of a display device provided in Embodiment 2 of the application;

FIG. 3 is a schematic structural diagram of a PFC component of a power supply component provided in Embodiment 3 of the application;

4 is a schematic diagram of the structure of the PFC component of the power supply component provided in the fourth embodiment of the application;

FIG. 5 is a schematic structural diagram of a PFC component of a power supply component provided in Embodiment 5 of the application;

6 is a schematic diagram of the structure of the PFC component of the power supply component provided in the sixth embodiment of the application;

FIG. 7 is a schematic structural diagram of a PFC component of a power supply component provided in Embodiment 7 of the application;

FIG. 8 is a schematic structural diagram of a PFC component of a power supply component provided in Embodiment 8 of the application;

FIG. 9 is a schematic diagram of the structure of the PFC component of the power supply component provided in the ninth embodiment of the application;

FIG. 10 is a schematic structural diagram of a display device provided in Embodiment 10 of this application;

FIG. 11 is a schematic flowchart of an overvoltage detection method provided in Embodiment 1 of this application.

Description of reference signs:

1—display assembly; 2—power supply assembly; 3—backlight assembly;

4—Shell; 5—Main board; 6—Audio component;

21—AC input circuit; 22—electromagnetic compatibility circuit; 23—rectifier circuit;

24-PFC component; 25-LLC circuit; 26-transformer;

27—Step-down circuit; 241—PFC circuit; 242—feedback circuit;

243—Regulation circuit; 244—Overvoltage protection circuit;

245—High frequency bypass filter capacitor; 246—Boost inductor;

247—large-capacity filter capacitor; 248—control switch;

249—Current detection circuit; 2411—Phase detection circuit;

2412—phase compensation circuit; 2413—frequency adjustment circuit.

detailed description

In order to make the purpose, technical solutions and advantages of this application clearer, the technical solutions in the embodiments of this application will be described clearly and completely in combination with the embodiments of this application. Obviously, the described embodiments are part of the implementation of this application. Examples, not all examples. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative work shall fall within the protection scope of this application.

The technical solutions provided in the present application will be exemplified below in conjunction with specific embodiments. In the following specific embodiments, the same or similar concepts or processes may not be repeated in some embodiments.

FIG. 1 is a schematic structural diagram of a display device provided in Embodiment 1 of this application. FIG. 1 exemplarily uses a television as the display device for illustration. As shown in FIG. 1, the TV includes a display screen assembly 1, a power supply assembly 2 (not shown in FIG. 1, and exemplarily, the power supply assembly 2 can be set at A in FIG. 1), a backlight assembly 3 and a housing 4. Among them, the display assembly 1 is used to present images to the user; the backlight assembly 3 is located below the display assembly 1, usually some optical components, used to supply sufficient brightness and uniformly distributed light sources, so that the display assembly 1 can display normally Image; the power supply assembly 2 is mainly used to receive the mains power supply and convert the mains power supply to supply power to the backlight assembly 3; the housing 4 is covered on the display assembly 1 to hide the backlight assembly 3, the power supply assembly 2 and other display devices Parts, play a beautiful effect.

In addition, the backlight assembly 3 also includes a backplane (not marked in FIG. 1), and the display device also includes a main board 5 (not shown in FIG. 1), and some convex structures are usually stamped on the backplane, the main board 5 and the power supply assembly 2. It is fixed on the convex hull by screws or hooks. The main board and the power supply assembly 2 are respectively provided with related circuits, and perform signal transmission and control. The circuit scheme involved on the power supply assembly 2 will be specifically introduced below.

2 is a schematic diagram of the structure of the power supply assembly of the display device provided in the second embodiment of the application. As shown in FIG. 2, the power supply assembly 2 mainly includes an AC input circuit 21, an electromagnetic compatibility (Electro Magnetic Compatibility, EMC) circuit 22, a rectifier circuit 23, a PFC component 24, a resonance conversion (LLC) circuit 25, a transformer 26, and Step-down circuit (BUCK circuit) 27. Among them, the electromagnetic compatibility circuit 22 is used to perform high-frequency filtering on the input AC power; the rectifier circuit 23 is used to rectify the input AC power and input a full-wave signal to the PFC component 24; the PFC component 24 generally includes PFC inductors and switching power devices With the PFC control chip, it mainly performs power factor correction on the input AC power supply and outputs a stable DC bus voltage (such as 380V) to the LLC circuit 25. The PFC component 24 can effectively improve the power factor of the power supply and ensure that the voltage and current are in the same phase; LLC The circuit 25 can step down or step up the DC bus voltage input by the PFC component 24 and output a constant voltage to the transformer 26. Exemplarily, the LLC circuit 25 may use a dual MOS tube LLC resonant conversion circuit. Generally, a synchronous rectification circuit is provided in the LLC circuit 25. The synchronous rectification circuit may mainly include a transformer, a controller, two MOS tubes, and a diode. In addition, the LLC circuit 25 may also include a pulse frequency modulation (Pulse frequency modulation, PFM) circuit, capacitors, inductors and other components. Generally, the LLC circuit 25 can output a variety of different voltages to meet the requirements of the load; the transformer 26 supplies power to the display screen assembly 1 and the backlight assembly 3 through the BUCK circuit 27. Exemplarily, the display device further includes an audio component 6, and the transformer 26 is also used to supply power to the main board 5 and the audio component 6.

FIG. 3 is a schematic diagram of the structure of the PFC component of the power supply component provided in the third embodiment of the application. As shown in FIG. 3, the PFC component 24 mainly includes: a PFC circuit 241 and a feedback circuit 242; among them,

The first terminal of the feedback circuit 242 is connected to the output terminal of the PFC component 24, and the second terminal of the feedback circuit 242 is connected to the feedback terminal of the PFC circuit 241;

The PFC circuit 241 is used to adjust the output voltage of the PFC component 24 so that the voltage at the feedback terminal of the PFC circuit 241 is consistent with the preset reference voltage; when the voltage at the feedback terminal is consistent with the preset reference voltage, the output voltage of the PFC circuit 241 is the preset Operating Voltage.

Exemplarily, one end of the feedback circuit 242 is connected to the output end of the PFC component 24, and the other end is connected to the feedback end of the PFC circuit 241 to form a feedback loop. The feedback loop is used to indicate the output voltage of the output terminal of the PFC component 24 to the PFC circuit 241. The PFC circuit 241 stores a preset reference voltage Vref. By comparing the voltage provided by the feedback loop at the feedback terminal of the PFC circuit 241 with the preset reference voltage, the output voltage of the PFC component 24 is adjusted, and finally the voltage at the feedback terminal is compared with the preset reference voltage. The reference voltage is the same. As a result, the output voltage of the PFC component 24 reaches the preset working voltage, which ensures the normal operation of the display device.

Exemplarily, as shown in FIG. 3, the PFC component 24 further includes a regulating circuit 243, the control end of the PFC circuit 241 is connected to the regulating circuit 243, and the regulating circuit 243 receives the voltage signal provided by the rectifying circuit 23. The PFC circuit 241 sends a driving signal to the adjustment circuit 243 through the control terminal, and the driving adjustment circuit 243 adjusts the voltage signal received from the rectifier circuit 23 and uses the adjustment result of the adjustment circuit 243 as the output voltage signal of the PFC component 24.

Exemplarily, the feedback circuit 242 is used to stabilize the voltage of the output terminal of the PFC component 24 at a preset voltage, such as 380V. Specifically, the feedback circuit 242 is used to feed back the voltage at the output terminal of the PFC component 24 to the PFC circuit 241, and the magnitude of the feedback voltage signal received by the feedback port of the PFC circuit 241 depends on the parameters of the devices in the feedback circuit 242. For example, when the voltage at the output terminal of the PFC component 24 is 380V, and the feedback voltage received by the PFC circuit 241 is 2.41V, the PFC circuit 241 can store the preset reference voltage 2.41V. When the feedback voltage received by the PFC circuit 241 is greater than 2.41V, the voltage at the output terminal of the PFC component 24 is reduced; when the feedback voltage received by the PFC circuit 241 is less than 2.41V, the voltage at the output terminal of the PFC component 24 is increased; thereby achieving a PFC component The voltage of the output terminal of 24 is stable.

However, when the feedback circuit 242 is abnormal, for example, the parameters of the device in the feedback circuit 242 change. For the same voltage signal output from the output terminal of the PFC component 24, the abnormal feedback circuit 242 provides the voltage signal to the PFC circuit 241 It is different from the voltage signal provided by the normal feedback circuit 242. At this time, the PFC circuit 241 still adjusts the output voltage of the PFC component 24 according to the abnormal feedback voltage signal, so that the voltage signal provided by the feedback circuit 242 to the PFC circuit 241 stabilizes at the preset reference voltage. Therefore, when the voltage signal provided by the feedback circuit 242 to the PFC circuit 241 is consistent with the preset reference voltage under abnormal conditions, the output voltage of the PFC component 24 cannot be stabilized at the normal operating voltage, and it is very likely to exceed the normal operating voltage. A safety failure may occur.

4 is a schematic diagram of the structure of the PFC component of the power supply component provided in the fourth embodiment of the application. Compared with the embodiment shown in FIG. 3, the PFC component in this embodiment further includes an overvoltage protection circuit 244. As shown in Figure 4,

The first terminal of the overvoltage protection circuit 244 is connected to the output terminal of the PFC component 24, the first terminal of the overvoltage protection circuit 244 is grounded, and the overvoltage detection terminal of the PFC circuit 241 is connected to the overvoltage indication terminal of the overvoltage protection circuit 244;

The over-voltage protection circuit 244 is used to indicate the output voltage of the output terminal of the PFC component 24 to the over-voltage detection terminal of the PFC circuit 241 through the over-voltage indication terminal; the PFC circuit 241 is after a preset period of time after the display device enters the working state. When the overvoltage detection terminal detects that the output terminal voltage of the PFC circuit 241 is greater than the preset operating voltage, the PFC circuit 241 is controlled to stop working.

When the PFC circuit 241 stops working, there is no output voltage at the output terminal of the PFC component 24.

Exemplarily, as shown in FIG. 4, the feedback circuit 242 and the overvoltage protection circuit 244 perform voltage protection on the output voltage of the PFC circuit 241 in two levels.

In this embodiment, an overvoltage protection circuit 244 is added to the output terminal of the PFC component 24 to indicate the output voltage of the output terminal of the PFC component 24 to the overvoltage detection terminal of the PFC circuit 241 through the overvoltage indication terminal. When the display device enters the working state, the overvoltage detection terminal of the PFC circuit 241 can monitor the output voltage of the output terminal of the PFC component 24 in real time through the overvoltage indicator terminal of the overvoltage protection circuit 244, and detect the PFC after a preset period of time Whether the voltage at the output terminal of the component 24 is greater than the preset operating voltage, if so, it can be considered that the feedback circuit 242 is faulty at this time, and the PFC circuit 241 needs to be controlled to stop working. When the PFC circuit 241 stops working, the regulating circuit 243 cannot receive the driving signal provided by the FPC circuit 241, and the regulating circuit 243 stops working, so that there is no output voltage at the output terminal of the PFC component 24.

Exemplarily, the preset time period may be the time required for the feedback circuit 242 to adjust the output voltage of the PFC component 24 to make the voltage of the feedback terminal consistent with the preset reference voltage after the display device enters the working state.

Exemplarily, the PFC circuit 241 is also connected to the main board 5 for acquiring the status of the display device, and the main chip of the display device may be provided on the main board 5.

The display device provided by the embodiment of the application monitors the output voltage of the PFC component by adding an overvoltage protection circuit at the output terminal of the PFC circuit, and controls the PFC circuit to stop working when the output voltage of the FPC component is greater than the preset operating voltage , Making the PFC component unable to output overvoltage, avoiding the display device from working under overvoltage conditions, and solving the problem of safety failures that may occur when the feedback circuit is abnormal due to only the feedback circuit.

Exemplarily, on the basis of the foregoing embodiment, a feasible overvoltage protection circuit 244 includes a voltage divider circuit composed of two resistors. One end of the voltage divider circuit is connected to the output end of the PFC component 24, and the other end is grounded. The overvoltage detection end of the PFC circuit 241 only needs to be connected to the voltage divider point of the voltage divider circuit to monitor the output circuit of the output end of the PFC component 24 in real time. When the PFC circuit 241 determines that the current output voltage of the FPC component is greater than the preset operating voltage according to the voltage of the voltage dividing point of the voltage divider circuit, the feedback circuit 242 is determined to be faulty. At this time, the regulating circuit 243 stops working, so that the FPC component has no output voltage. It also causes the overvoltage protection circuit 244 to stop working. The overvoltage protection circuit has a simple structure and low cost, and can realize overvoltage protection for the PFC component when the feedback circuit 242 fails.

However, taking the display device as a TV set as an example, in addition to the above-mentioned overvoltage state, the display device includes a working state, a standby state, and a shutdown state when there is no fault. The working state of the display device can be for the user to turn on the TV and watch TV programs, and the standby state of the display device can be for the user to turn off the display function of the TV through the remote control. Some functional modules of the TV are still powered on. In the standby state, the power Component 2 is still working.

When the display device is in the standby state, if the overvoltage protection circuit 244 adopts the voltage divider circuit structure composed of the above two resistors, since the power supply component 2 is still working, the output terminal of the PFC component still outputs voltage normally, so that the voltage protection circuit 244 It has been in working condition, so there is a large power consumption.

Exemplarily, on the basis of the foregoing embodiment, an embodiment of the present application further provides a display device. FIG. 5 is a schematic structural diagram of a PFC component of a power supply component provided in Embodiment 5 of the application. This embodiment discloses another possible structure of the overvoltage protection circuit 244. As shown in FIG. 5, the overvoltage protection circuit 244 includes a first resistor R1, a second resistor R2, and a switch K;

The first end of the first resistor R1 is connected to the output end of the PFC component 24, the second end of the first resistor R1 is connected to the first end of the switch K, and the second end of the switch K is respectively connected to the overvoltage detection end of the PFC circuit 241 The first end of the second resistor R2 is connected, the control end of the switch K is connected to the control end of the PFC circuit 241, and the second end of the second resistor R2 is grounded.

When the display device is in the standby state, the control terminal of the PFC circuit 241 provides the control terminal of the switch K of the overvoltage protection circuit 244 with a driving signal whose duty cycle is less than the preset duty cycle, or stops the signal to the overvoltage protection circuit 244 The control terminal of the switch K outputs a driving signal to turn off the switch K.

Exemplarily, when the switch K is turned on, the first resistor R1 and the second resistor R2 form a voltage divider circuit. When the switch K is turned off, the overvoltage protection circuit 244 stops working, and no power consumption occurs. When the PFC circuit 241 controls the switch K to be turned on and off according to the driving signal with a small duty ratio, the overvoltage protection circuit 244 can be operated in a low power consumption state.

Exemplarily, the switch K in this embodiment may be a controllable element, for example, the switch may be a triode or a MOS transistor.

The overvoltage protection circuit provided by this embodiment has a simple structure and low cost. It not only prevents the display device from working under overvoltage conditions, but also solves the problem of safety failures that may occur when the feedback circuit is abnormal due to only the feedback circuit. At the same time, waste of power consumption is avoided.

Exemplarily, when the PFC circuit 241 is a PFC chip, the control terminal of the PFC circuit 241 may be the original OUT pin (drive signal output pin) of the PFC chip, thereby avoiding the introduction of the overvoltage protection circuit 244 in the display device. The dedicated control circuit has a simple structure and reduces the cost.

It can be understood that the PFC component 24 can also be other circuit modules that need to provide a stable voltage at the output end. Applying the feedback circuit 242 and the overvoltage protection circuit 244 in the embodiment of the present application to the circuit modules that need to provide a stable voltage at the output end can realize the double-layer overvoltage protection of these circuit modules. The low-power over-voltage protection implemented by the feedback circuit 242 and the over-voltage protection circuit 244 in the embodiments of the present application can also be applied to other household appliances other than display devices, and even other power electronic devices. The various embodiments of the present application and The drawings only take the power factor correction PFC component as an example for illustrative description, and do not limit the application.

Exemplarily, as shown in FIG. 5, the overvoltage protection circuit 244 further includes: a third resistor R3 and a first capacitor C1;

The control terminal of the switch K is also connected to the first terminal of the third resistor R3 and the first capacitor C1 respectively, and the second terminal of the third resistor R3 and the first capacitor C1 are grounded.

In the display device provided in this embodiment, a third resistor and a first capacitor are added to the overvoltage protection circuit, which can play a filtering role, and can provide a higher quality driving signal for the overvoltage protection circuit.

Exemplarily, on the basis of any of the foregoing embodiments, an embodiment of the present application further provides a display device. This embodiment discloses a feasible circuit structure of the feedback circuit 242.

FIG. 6 is a schematic diagram of the structure of the PFC assembly of the power supply assembly provided in the sixth embodiment of the application. As shown in FIG. 6, the feedback circuit 242 includes: a first resistor R4 and a fifth resistor R5;

The first end of the first resistor R4 is connected to the output end of the PFC component 24, the second end of the first resistor R4 is respectively connected to the first end of the fifth resistor R5 and the feedback end of the PFC circuit 241, and the second end of the fifth resistor R5 Two ends are grounded;

The feedback circuit 242 is configured to determine the voltage provided at the feedback terminal of the PFC circuit 241 according to the resistance value of the fourth resistor R4, the resistance value of the fifth resistor R5 and the output voltage of the PFC component 24;

When the resistance of the fourth resistor R4 and/or the fifth resistor R5 changes, when the PFC circuit 241 adjusts the output voltage of the PFC component 24 so that the voltage at the feedback terminal is consistent with the preset reference voltage, the output of the PFC component 24 The voltage does not match the preset operating voltage.

Exemplarily, referring to FIG. 6, the feedback circuit 242 determines the voltage V1 of the feedback terminal according to the output voltage Vout of R4, R5 and the PFC component 24 using the following formula 1:

V1=Vout*R5/(R4+R5) Formula 1

Exemplarily, the PFC circuit 241 compares the preset reference voltage Vref and V1. When Vref is greater than V1, it can be determined that the output voltage of the output terminal of the PFC component 24 is too high Vout. At this time, the PFC circuit 241 lowers the output voltage of the PFC component 24. Output voltage; when Vref is less than V1, it can be determined that the output voltage of the output terminal of the PFC component 24 is lower than Vout. At this time, the PFC circuit 241 increases the output voltage of the output terminal of the PFC component 24; through multiple adjustments, until Vref is consistent with V1 .

It is understandable that when the resistance value of the fourth resistor R4 and/or the fifth resistor R5 changes, the PFC circuit 241 adjusts the output voltage of the PFC component 24 according to V1 and Vref, so that when V1 and Vref are the same, the PFC component The output voltage of 24 is inconsistent with the preset operating voltage.

For example, the value of Vref can be set to 2.41V. When the feedback loop is normal, the resistance values of the fourth resistor R4 and the fifth resistor R5 are: R4=8800KΩ, R5=56.2KΩ. When Vout=380V, V1=380*56.2/(8800+56.2)=2.41V. When Vout=400V, which is greater than 380V, V1=2.54V, which is greater than Vref. At this time, the PFC circuit 241 can adjust Vout to lower Vout so that Vout is stabilized at 380V.

However, when an abnormality occurs in the feedback loop, for example, the resistance of the fifth resistor R5 increases and becomes R5=80KΩ. When Vout=380V, V1=380*80/(8800+80)=3.42V, which is greater than Vref. At this time, the PFC circuit 241 will lower Vout, that is, when Vout is stable at 380V, the feedback loop is abnormal. , The PFC circuit 241 stabilizes Vout at a voltage value lower than the preset operating voltage. When the resistance of the fifth resistor R5 decreases, for example, it becomes R5=50KΩ. When Vout=380V, V1=380*50/(8800+50)=2.15V, which is less than Vref. At this time, the PFC circuit 241 will increase Vout, that is, when Vout is stable at 380V, due to abnormalities in the feedback loop, The PFC circuit 241 increases Vout to a voltage value much higher than the preset operating voltage. Therefore, the overvoltage protection circuit 244 in the above-mentioned embodiment can be added to the output end of the PFC component 24 to avoid the problem of safety failure when the feedback circuit is abnormal due to only the feedback circuit.

When an abnormality occurs in the feedback loop, the voltage signal provided by the overvoltage indication terminal of the overvoltage protection circuit 244 to the overvoltage detection terminal of the PFC circuit 241 is different from the normal state. When it is determined according to the voltage signal provided by the overvoltage indicator terminal of the overvoltage protection circuit 244 that the voltage at the output terminal of the PFC circuit 241 is greater than the preset operating voltage, the PFC circuit 241 can control the PFC circuit 241 to stop working, and the output terminal of the PFC component 24 stops outputting Voltage, thereby realizing the overvoltage protection of the output end of the PFC component 24.

In the display device provided by this embodiment, the feedback circuit has a simple structure and a low cost.

Exemplarily, as shown in FIG. 6, the feedback circuit 242 further includes: a second capacitor C2 connected in parallel with the fifth resistor R5;

The feedback circuit 242 is specifically used to determine the voltage of the feedback terminal according to the resistance value of the fourth resistor R4, the resistance value of the fifth resistor R5, the resistance value of the second capacitor C2, and the output voltage of the PFC component 24.

Exemplarily, the second capacitor C2 is a filter capacitor, which is used to filter high frequency signals and provide a higher quality voltage signal for the PFC circuit 241.

Exemplarily, the feedback circuit 242 determines the voltage V1 of the feedback terminal according to R4, R5, C2 and the output voltage Vout of the PFC component 24, specifically using the following formula 2:

_And V1 = Vout * R / (R4 + R _and) formula 2

Among them, R _and = R5//C2, R5//C2 means that R5 is connected in parallel with C2.

It can be understood that when at least one of the fourth resistor R4, the fifth resistor R5, and the second capacitor C2 fails, the PFC circuit 241 adjusts the output voltage of the PFC component 24 according to V1 and Vref, which will make V1 and Vref consistent. At this time, the output voltage of the PFC component 24 is not consistent with the preset operating voltage. Similarly, when at least one of the fourth resistor R4, the fifth resistor R5, and the second capacitor C2 fails, the PFC circuit 241 can control the PFC circuit 241 to stop working, and the output terminal of the PFC component 24 stops outputting voltage, thereby achieving Overvoltage protection of the output terminal of the PFC component 24.

In the display device provided by this embodiment, a second capacitor is added to the feedback circuit, which can filter out high-frequency signals in the display device, and can provide a higher quality voltage signal for the PFC circuit.

Exemplarily, on the basis of the foregoing embodiment, an embodiment of the present application further provides a display device. FIG. 7 is a schematic structural diagram of a PFC component of a power supply component provided in Embodiment 7 of the application. This embodiment describes the structure of the PFC circuit in detail. As shown in FIG. 7, the PFC circuit 241 includes: a phase detection circuit 2411, a phase compensation circuit 2412, and a frequency adjustment circuit 2413; among them,

The phase detection circuit 2411 is used to detect whether the phases of the output voltage and the output current of the PFC component 24 are consistent;

The frequency adjustment circuit 2413 is used to adjust the frequency of the output voltage of the PFC component 24 when the output voltage of the PFC component 24 is inconsistent with the phase of the output current, so as to reduce the phase inconsistency of the output voltage and the output current of the PFC component 24;

The phase compensation circuit 2412 is used to stabilize the output voltage of the PFC component 24.

Exemplarily, on the basis of the foregoing embodiment, an embodiment of the present application further provides a display device. FIG. 8 is a schematic structural diagram of a PFC component of a power supply component provided in Embodiment 8 of the application. As shown in FIG. 8, the control terminal of the overvoltage protection circuit 244 is also connected to the control terminal of the LLC circuit 25.

Exemplarily, as shown in FIGS. 8 and 2, the power supply assembly 2 of the display device includes a PFC assembly 24 and an LLC circuit 25. The PFC component 24 and the LLC circuit 25 can be integrated. The driving signal received by the control terminal of the overvoltage protection circuit 244 may be a driving signal provided by the PFC circuit 241 or a driving signal provided by the LLC circuit 25.

Specifically, the control terminal of the overvoltage protection circuit 244 may only be connected to the control terminal of the PFC circuit 241, or only the control terminal of the LLC circuit 25. The control terminal of the overvoltage protection circuit 244 can also be connected to the control terminals of the PFC circuit 241 and the LLC circuit 25 as shown in FIG. 8.

Exemplarily, when the display device is in the working state, the PFC circuit 241 and/or LLC circuit 25 outputs a driving signal through the control terminal, and controls the switch K to be turned on, so that the overvoltage protection circuit 244 overvoltages the output terminal of the PFC component 24 protection.

When the display device is in the standby state, the control terminal of the PFC circuit 241 and/or LLC circuit 25 stops outputting driving signals or outputting driving signals with a duty cycle less than a preset duty cycle, so that the overvoltage protection circuit 244 stops working on the PFC circuit 241 The output terminal is protected against overvoltage, thereby reducing power consumption in the standby state.

On the basis of any of the foregoing embodiments, FIG. 9 is a schematic structural diagram of a PFC component of a power supply component provided in Embodiment 9 of this application. As shown in FIG. 9, the PFC component 24 further includes: a high-frequency bypass filter capacitor 245, a boost inductor 246, a large-capacity filter capacitor 247, a control switch 248, and a current detection circuit 249.

Exemplarily, the high-frequency bypass filter capacitor 245 in this embodiment is connected to the output terminal of the rectifier circuit 23, and is used to filter the high-frequency current of the output voltage of the rectifier circuit 23 and to store electric energy. The boost inductor 246 is connected to the high-frequency bypass filter capacitor 245 to maintain energy when the voltage is disconnected.

Exemplarily, the adjustment circuit 243 is connected to the boost inductor 246, the control switch 248, and the large-capacity filter capacitor 247, respectively. When the control switch 248 is turned off, the adjustment circuit 243 is turned off to store energy to form a boost boost circuit. By controlling the duty cycle of the on and off of the switch 248, the output voltage of the PFC component 24 is affected.

The current detection circuit 249 can be used to implement the function of the phase detection circuit 2411. The PFC circuit 241 and the control switch 248 in this embodiment can be used to implement the frequency adjustment function of the frequency adjustment circuit 2413.

Illustratively, the PFC circuit 241 adopts the L6562D chip as an example below to describe in detail the structure of the power supply assembly in the display device provided in the embodiment of the present application.

FIG. 10 is a schematic structural diagram of a display device provided in Embodiment 10 of this application. As shown in FIG. 10, the display device includes a filter circuit, a rectifier circuit 23, an L6562D chip and a transformer 26.

Exemplarily, the power supply supplies power to the PFC assembly 24 through the filter circuit and the rectifier circuit 23. The transformer 26 is used to supply power to other power-consuming parts of the display device (for example, the display screen assembly 1, the backlight assembly 3, the main board 5 and the audio assembly 6). The L6562D chip can be an integrated PFC chip and LLC chip.

As shown in Figure 10, the L6562D chip includes pins VCC, GND, FB, PFC DRV, PFCCS, OVP, LCS, LLC DRV, HSGND and HSDRV. Among them, the VCC pin is connected to the DC power supply, and VCC represents the DC power supply. The GND pin is connected to ground. The FB pin is connected to the feedback circuit 242. The feedback circuit 242 in FIG. 10 includes resistors R890 and R809, and a capacitor C886. The function of the PFC DRV pin is equivalent to the drive signal output terminal of the PFC circuit 241 in the above embodiment. The PFC DRV pin is used to output a driving signal to the overvoltage protection circuit 244. When the driving signal stops or the duty cycle is less than the preset duty cycle, the overvoltage protection circuit 244 stops performing overvoltage protection on the output voltage of the PFC component 24. The PFCCS pin and the LSC pin are used to implement the function of the phase detection circuit 2411 in the above embodiment. The OVP pin is used to connect to the overvoltage indicator end of the overvoltage protection circuit 244. The overvoltage protection circuit 244 in FIG. 10 includes resistors R810 and R811, and a switch V830. The control terminal of the switch V830 is connected to the PFC DRV pin. The LLC DRV pin is also used to output a driving signal to the overvoltage protection circuit 244. LLC DRV pin and HS DRV pin are used to drive transformer 26. The HSGND pin is used to connect to the transformer 26.

Exemplarily, the adjusting circuit 243 in the foregoing embodiment may be the freewheeling diode D in the embodiment shown in FIG. 10. The high-frequency bypass filter capacitor 245 in the embodiment shown in FIG. 9 may be the capacitor C3 in the embodiment shown in FIG. 10. The boost inductor 246 in the embodiment shown in FIG. 9 may be the inductor L in the embodiment shown in FIG. 10. The large-capacity filter capacitor 247 in the embodiment shown in FIG. 9 may be the capacitor C4 in the embodiment shown in FIG. 10. The control switch 248 in the embodiment shown in FIG. 9 may be the switch K1 in the embodiment shown in FIG. 10. The current detection circuit 249 in the embodiment shown in FIG. 9 may be the resistor R6 in the embodiment shown in FIG. 10.

Another aspect of the present application also provides an overvoltage detection method, which is applied to a display device, and the display device includes a PFC circuit. Exemplarily, the display device in this embodiment may be the display device in any of the embodiments in FIGS. 1-10.

FIG. 11 is a schematic flowchart of an overvoltage detection method provided in Embodiment 1 of this application. As shown in Figure 11, the method includes:

S101. Acquire the status of the display device;

S102: When the display device enters the standby state, stop performing overvoltage protection on the output terminal of the PFC circuit.

Exemplarily, in a possible implementation manner, the display device includes an overvoltage protection circuit, and stopping the overvoltage protection of the output terminal of the PFC circuit may specifically include:

Output a driving signal with a duty cycle less than the preset duty cycle to the overvoltage protection circuit, or stop outputting the driving signal to the overvoltage protection circuit.

It is worth noting that, on the basis of the implementation provided by the above-mentioned embodiments, the present application can be further combined to provide more embodiments.

The device in this embodiment and the method in the foregoing embodiment are based on two aspects under the same inventive concept. The implementation process of the method has been described in detail above, so those skilled in the art can clearly understand the present invention based on the foregoing description. For the sake of brevity of the description, the structure and implementation process of the system in implementation will not be repeated here.

In the several embodiments provided in this application, it should be understood that the disclosed system, device, and method may be implemented in other ways. For example, the device embodiments described above are only illustrative. For example, the division of the units is only a logical function division, and there may be other divisions in actual implementation, for example, multiple units or components can be combined or It can be integrated into another system, or some features can be ignored or not implemented. In addition, the displayed or discussed mutual coupling or direct coupling or communication connection may be indirect coupling or communication connection through some interfaces, devices or units, and may be in electrical, mechanical or other forms.

The terms "first", "second", "third", "fourth", etc. in the description and claims of this application and the above-mentioned drawings are used to distinguish similar objects, and not necessarily used to describe a specific sequence Or precedence. It should be understood that the data used in this way can be interchanged under appropriate circumstances so that the embodiments described herein can be implemented in an order other than the content illustrated or described herein. In addition, the terms "including" and "having" and any variations of them are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to the clearly listed Those steps or units may include other steps or units that are not clearly listed or are inherent to these processes, methods, products, or equipment. The terms "including" and "including", as well as their derivative expressions, all mean including without limitation.

A person of ordinary skill in the art can understand that all or part of the steps in the foregoing method embodiments can be implemented by a program instructing relevant hardware. The aforementioned program can be stored in a computer readable storage medium. When the program is executed, the steps including the foregoing method embodiments are executed; and the foregoing storage medium includes: ROM, RAM, magnetic disk, or optical disk and other media that can store program codes.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the application, not to limit them; although the application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand: It is still possible to modify the technical solutions described in the foregoing embodiments, or equivalently replace some or all of the technical features; these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the technical solutions of the embodiments of the application range.

Claims

A display device includes a circuit board, the circuit board includes: a feedback circuit, an overvoltage protection circuit, and a functional circuit; wherein,

The output terminal of the functional circuit is respectively connected to the first terminal of the feedback circuit and the first terminal of the overvoltage protection circuit, and the second terminal of the feedback circuit is connected to the feedback terminal of the functional circuit. The second terminal of the overvoltage protection circuit is grounded, and the overvoltage detection terminal of the functional circuit is connected to the overvoltage indication terminal of the overvoltage protection circuit;

The feedback circuit is used to determine the voltage of the feedback terminal according to the output voltage of the output terminal of the functional circuit;

The overvoltage protection circuit is configured to indicate the output voltage of the output terminal to the overvoltage detection terminal of the functional circuit through the overvoltage indication terminal;

The functional circuit is used to adjust the output voltage of the functional circuit so that the voltage of the feedback terminal is consistent with the preset reference voltage; when the voltage of the feedback terminal is consistent with the preset reference voltage, the output of the functional circuit The voltage is the preset working voltage;

The functional circuit is further configured to control the output voltage of the functional circuit to be greater than the preset operating voltage after the overvoltage detection terminal detects that the output voltage of the functional circuit is greater than the preset operating voltage after a preset period of time after the display device enters the working state The functional circuit stops working.
The display device according to claim 1, wherein the control terminal of the functional circuit is connected to the control terminal of the overvoltage protection circuit, and is used to control the working state of the overvoltage protection circuit;

The functional circuit is also used to control the overvoltage protection circuit to stop performing overvoltage protection on the output terminal of the functional circuit when the display device is in a standby state.
The display device according to claim 2, when the display device is in a standby state, the functional circuit is specifically configured to provide a drive with a duty cycle smaller than a preset duty cycle to the control terminal of the overvoltage protection circuit Signal, or, stop providing a drive signal to the control terminal of the overvoltage protection circuit.
The display device according to any one of claims 1-3, the overvoltage protection circuit comprises: a first resistor, a second resistor, and a switch;

The first end of the first resistor is connected to the output end of the functional circuit, the second end of the first resistor is connected to the first end of the switch, and the second end of the switch is connected to the functional circuit respectively. The overvoltage detection terminal of the circuit is connected to the first terminal of the second resistor, the control terminal of the switch is connected to the control terminal of the functional circuit, and the second terminal of the second resistor is grounded.
4. The display device of claim 4, the overvoltage protection circuit further comprises: a third resistor and a first capacitor;

The control terminal of the switch is also connected to the first terminal of the third resistor and the first capacitor respectively, and the second terminal of the third resistor and the first capacitor are grounded.
The display device according to any one of claims 1-3, the feedback circuit comprises: a fourth resistor and a fifth resistor;

The first end of the fourth resistor is connected to the output end of the functional circuit, and the second end of the fourth resistor is respectively connected to the first end of the fifth resistor and the feedback end of the functional circuit, so The second end of the fifth resistor is grounded;

The feedback circuit is configured to determine the voltage of the feedback terminal according to the resistance value of the fourth resistor, the resistance value of the fifth resistor, and the output voltage of the functional circuit;

When the resistance value of the fourth resistor and/or the fifth resistor changes, when the functional circuit adjusts the output voltage of the functional circuit so that the voltage of the feedback terminal is consistent with the preset reference voltage, The output voltage of the functional circuit is inconsistent with the preset operating voltage.
8. The display device of claim 6, the feedback circuit further comprising: a second capacitor connected in parallel with the fifth resistor;

The feedback circuit is specifically configured to determine the voltage of the feedback terminal according to the resistance value of the fourth resistor, the resistance value of the fifth resistor, the resistance value of the second capacitor, and the output voltage of the functional circuit .
The display device according to any one of claims 1 to 3, wherein the functional circuit is a PFC component, and the PFC component includes a power factor correction PFC circuit;

The output terminal of the PFC component is connected to the first terminal of the feedback circuit and the first terminal of the overvoltage protection circuit, and the second terminal of the feedback circuit is connected to the feedback terminal of the PFC circuit. The overvoltage detection terminal of the PFC circuit is connected to the overvoltage indication terminal of the overvoltage protection circuit.
An overvoltage detection method for a display device, the display device including a PFC circuit, and the method includes:

Get the status of the display device;

When the display device enters the standby state, stop performing overvoltage protection on the output terminal of the PFC circuit.
The method according to claim 9, wherein the display device includes an overvoltage protection circuit, and the stopping the overvoltage protection of the output terminal of the PFC circuit includes:

Outputting a driving signal with a duty ratio less than a preset duty ratio to the overvoltage protection circuit, or stopping outputting the driving signal to the overvoltage protection circuit.