TW201405511A - Display system and over-voltage protection device - Google Patents

Abstract

An over-voltage protection device of display system is disclosed, including a sampling module and a control module. The sampling module receives a first supply voltage and a second supply voltage that are outputted by the power conversion module for the backlight module and panel peripheral circuit, respectively, and obtains a detection voltage after processed by the sampling module; the control module performs analog/digital conversion of the detection voltage outputted from sampling module into a detection value, and compares the detection value with a built-in reference value. If it is determined that the detection value is not greater than the reference value, the enabling supply voltage is outputted to the power conversion module so as to be in a working mode; on the other hand, if the detection value is greater than the reference value, the disabling supply voltage is outputted to the power conversion module so as to be in a sleep mode.

Description

Display system and overvoltage protection device

The invention relates to a display system and a voltage protection device, in particular to a display system and an overvoltage protection device capable of accurately determining an overvoltage condition, thereby controlling the output of the operating voltage, thereby preventing damage to its internal components.

Referring to FIG. 1 , a high-power liquid crystal display system 9 includes a motherboard control circuit 90 , a power conversion device 91 , a panel peripheral circuit 92 , a backlight module 93 , an energy saving control circuit 97 , and an overvoltage protection circuit . 98. The backlight module 93 has an LED driving circuit 931 and an LED light source 932. The components are respectively described below.

The power conversion device 91 includes an EMI (Electro Magnetic Interference) filter circuit 911, a bridge rectifier circuit 912, a PFC (Power Factor Correction) circuit 913, a main power conversion circuit 914, and a standby power conversion. The circuit 916, wherein the EMI filter circuit 911 receives the input of the AC mains (such as 90-264Vac) signal to filter out the conductive electromagnetic interference therein, the bridge rectifier circuit 912 performs full-wave rectification, and the PFC circuit 913 corrects the current waveform and filters. Generate DC bus voltage Vbus (for example: about 400V).

The main power conversion circuit 914 receives the bus voltage Vbus and performs step-down conversion to output a first supply voltage Vm1 (eg, 24V) and a second supply voltage Vm2 (eg, 12V), wherein the first supply voltage Vm1 is further passed through the LED drive circuit 931 After the voltage conversion, an operating voltage capable of driving the LED light source 932 is generated. The second power supply voltage Vm2 provides a panel peripheral circuit 92, such as a liquid crystal panel driver circuit (Panel Driver Circuit) and an audio circuit (Audio Circuit).

The standby power conversion circuit 916 receives the bus voltage Vbus and performs step-down conversion to output a standby power supply voltage Vsb (eg, 5 volts) to the power saving control circuit 97, the overvoltage protection circuit 98, and the liquid crystal display system 9 such as a motherboard image processor. In addition, the transformer auxiliary winding voltage in the standby power conversion circuit 916 is rectified and filtered to generate an auxiliary power supply voltage Vaux (eg, 12-19 volts).

Referring to FIGS. 1 and 2, the main power conversion circuit 914 has a controller 940, the power factor correction circuit 913 has a controller 930, and the controllers 930, 940 are controlled by the energy saving control circuit 97, and the power saving control circuit 97 includes the switching element Q1. , Q2, Q3, resistors R1-R7, capacitors C1 and C2, diode D1, optical coupler OC1 and Zener diode ZD1. The overvoltage protection circuit 98 includes switching elements Q4, Q5, resistors R8-R12, capacitor C3, diodes D2-D4, and Zener diodes ZD2, ZD3. The overvoltage protection circuit 98 can provide an overvoltage protection function of the first supply voltage Vm1 and the second supply voltage Vm2. When the output voltage of the first supply voltage Vm1 or the second supply voltage Vm2 is abnormal and reaches an overvoltage protection point, the overvoltage protection The circuit 98 turns off the transistor Q3 inside the control power-saving control circuit 97, so that the controller 930 in the PFC circuit 913 and the controller 940 in the main power conversion circuit 914 do not get the Vcc supply voltage and stop working, and finally the main power supply is switched. The circuit 914 has no output voltage of the first supply voltage Vm1 and the second supply voltage Vm2 to protect the LED drive circuit 931 or the periphery of the panel The electronic components inside the circuit 92 are not damaged, and the principle is explained below.

When the liquid crystal display system 9 is working normally, the main board control circuit 90 controls the power-on pin PS_ON to be at a high potential. At this time, the switching elements Q1 and Q2 of the energy-saving control circuit 97 are turned on, and the LED of the input side of the optocoupler OC1 has a current flowing. The photosensitive switching element on its output side is turned on, so that the switching element Q3 is turned on, so that the auxiliary power supply voltage Vaux can supply the internal power supply voltage Vcc to the PFC circuit 913 and the controllers 930, 940 in the main power conversion circuit 914 through the switching element Q3. The power supply is such that the PFC circuit 913 and the main power conversion circuit 914 operate normally under the control of the controllers 930, 940 during normal operation to perform voltage conversion.

When the liquid crystal display system 9 is in the standby mode, the main board control circuit 90 controls the power-on pin PS_ON to be at a low potential, and at this time, the switching elements Q1 and Q2 are turned off, and the LED on the input side of the photocoupler OC1 has no current flowing through the output side thereof. The photosensitive switching element is turned off, causing the switching element Q3 to be turned off, so that the auxiliary power supply voltage Vaux cannot supply the internal power supply voltage Vcc to the PFC circuit 913 and the controller 930, 940 in the main power conversion circuit 914 through the switching element Q3, so that it is in standby. In the mode, the PFC circuit 913 and the main power conversion circuit 914 can be operated more stably because the controllers 930 and 940 are turned off.

As for the function of the overvoltage protection circuit 98, when neither the first supply voltage Vm1 nor the second supply voltage Vm2 exceeds the value of the respective overvoltage protection point, the overvoltage protection circuit 98 does not affect the overvoltage protection pin terminal. OVP input voltage. However, when the first supply voltage Vm1 or the second supply voltage Vm2 exceeds the value of the respective overvoltage protection point, the Zener diode ZD2 or ZD3 is turned on and turned on, generating a current through resistors R8 and R9, causing the base terminal to the emitter terminal voltage Vbe5 of the switching element Q5 to rise. When the voltage Vbe5 reaches the turn-on voltage, the switching element Q5 is turned on, so that the base terminal voltage Vb4 of the switching element Q4 is pulled low to turn on the switching element Q4, thereby causing the switching element Q5 to be in a saturated conducting state, causing the voltage Vb4 to be pulled to a minimum. The switching element Q4 is also in a saturated conduction state. At this time, since the cathode terminal voltage of the diode D4 (ie, the voltage Vb4) is pulled to the minimum, the voltage of the overvoltage protection pin terminal OVP (ie, the anode terminal voltage of the diode D4) is pulled down, resulting in the optical coupler. The LED on the input side of the OC1 has no current passing through, so that the photosensitive switching element on the output side thereof is turned off, causing the switching element Q3 to be turned off, so that the auxiliary power supply voltage Vaux cannot supply the internal power supply voltage Vcc to the PFC circuit 13 and the main power conversion circuit through the switching element Q3. The controllers 930, 940 of 14 require power, so when the first supply voltage Vm1 or the second supply voltage Vm2 has an overvoltage, the PFC circuit 13 and the main power conversion circuit 14 will be stopped due to the controllers 930, 940 being turned off. It can prevent other circuits from being destroyed.

The diode D1 of the energy-saving control circuit 97 is for ensuring the voltage drop of the LED falling on the input side of the photocoupler OC1 caused by the overvoltage protection circuit 98 when there is an overvoltage at the first supply voltage Vm1 or the second supply voltage Vm2 ( That is, Vf4+Vce5-Vf1=0.7V+0.2V-0.7V=0.2V) will not let the LED turn on and the LED has no current, wherein Vf4 and Vf1 are the forward voltage drop of the diodes D4 and D1, respectively. Vce5 is the extreme to emitter extreme voltage when transistor Q5 is saturated.

The technique of the known overvoltage protection circuit 98 is missing as follows:

1. The difference between the upper and lower limits of Zener diode ZD2 and ZD3 voltage regulation is large, which will cause a large difference in OVP overvoltage protection points of different power supply boards.

2. The Zener diodes ZD2 and ZD3 still have leakage current Ir before they are turned on. When their body temperature increases, the leakage current will increase. If the resistance values of resistors R8 and R9 are not reasonable, the temperature is high. In a high-humidity environment, the leakage current of the Zener diodes ZD2 and ZD3 is likely to increase, causing malfunction of the switching element Q5, so that the main power source is turned off.

3. During normal operation, the negative terminal voltage of the diode D4 is greater than the positive terminal voltage, so that the diode D4 is reversely turned off, but the diode D4 usually has a large Ir reverse leakage current when high temperature and high humidity. Under the environment, the reverse leakage current of the diode D4 increases. If the resistance of the resistor R12 is set too large, the reverse leakage current of the diode D4 causes a voltage difference across the resistor R12. V=R12 ^* Ir, when the voltage difference is large, the switching element Q4 starts to conduct, the switching element Q4 is turned on to generate a current at the collector and the emitter, so that the switching element Q5 is turned on, and finally, the switching elements Q4 and Q5 are all in a saturated conduction state. When the protection circuit malfunctions.

4, the general experience is not very rich, engineers are difficult to make a very correct choice for all electronic components in the circuit, if some of the parameters of the parts are not set properly, such as: the resistance R9, R12 resistance set too large, high temperature Under wet conditions, it is easy to cause malfunction.

Accordingly, it is an object of the present invention to provide a display system and overvoltage protection device that overcomes the deficiencies of the prior art.

Therefore, the overvoltage protection device of the display system of the present invention cooperates with the display The display system has a power conversion module, a panel peripheral circuit, a backlight module and an energy saving control circuit, and the energy saving control circuit is controlled by the overvoltage protection device to output a power supply voltage.

The overvoltage protection device comprises a sampling module and a control module. The sampling module is electrically connected to the power conversion module, and receives a first power supply voltage outputted by the power conversion module to the backlight module, and receives a second power supply voltage outputted by the power conversion module to the peripheral circuit of the panel. And the detection module is processed to obtain a detection voltage; the control module is electrically connected to the sampling module and the energy-saving control circuit, and the detection voltage analog/digital digit outputted by the sampling module is converted into a detection value. And comparing the detected value with a built-in reference value, if it is determined that the detected value is not greater than the reference value, controlling the energy-saving control circuit to enable the power supply voltage output, so that the power conversion module is in an operating mode If it is determined that the detection value is greater than the reference value, controlling the energy-saving control circuit to disable the power supply voltage output, so that the power conversion module is in a sleep mode, that is, the main power conversion circuit 314 is turned off without outputting Vm1 and Vm2 voltage.

The display system of the present invention comprises a power conversion module, a panel peripheral circuit, a backlight module, an energy saving control circuit and an overvoltage protection device.

The power conversion module converts a commercial power into a first power supply voltage, a second power supply voltage, and a third power supply voltage, and is driven by a power supply voltage to convert the power conversion function; the backlight module is electrically connected to the power conversion mode The group is driven by the first power supply voltage to operate normally; the peripheral circuit of the panel is electrically connected to the power conversion module, and is driven by the second power supply voltage to operate normally; the energy-saving control circuit is electrically connected to the power conversion module. Receiving the third supply voltage as a power supply of the energy saving control circuit, and the energy saving control circuit further receives the slave a power supply voltage outputted by the standby power conversion circuit in the power conversion module, and can be disabled by the overvoltage protection device or enabled to output the power supply voltage to the controller and the main circuit of the PFC circuit in the power conversion module Controller for the power conversion circuit.

The overvoltage protection device is electrically connected to the power conversion module, and includes a sampling module and a control module; the sampling module receives the first supply voltage and the second supply voltage output by the power conversion module, and After the sampling module processes, a detection voltage is obtained; the control module converts the detected voltage analog/digital value into a detection value, and compares the detection value with a built-in reference value, if the detection is determined If the measured value is not greater than the reference value, the energy-saving control circuit is controlled to enable the power supply voltage output, so that the power conversion module is in the working mode; if the detected value is greater than the reference value, the energy-saving control circuit is disabled. The power supply voltage output causes the power conversion module to be in a sleep mode, that is, the first power supply voltage output by the power conversion module or the second power supply voltage is caused by an overvoltage, so that the main power conversion circuit in the power conversion module is turned off. Drop it.

Preferably, the power conversion module has a controller of a PFC circuit and a controller of a main power conversion circuit, and the controller of the PFC circuit and the controller of the main power conversion circuit are controlled by the supply voltage in the working mode. Or the sleep mode. The control module is an image processor of the motherboard control circuit. The sampling module has a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a first diode, a second diode, and a a first capacitor; the first resistor is coupled in series with the second resistor and coupled between the first supply voltage and the ground, and the connection end of the first resistor and the second resistor is coupled to the first diode The anode end of the body, the first diode The cathode end is coupled to the analog to digital conversion input of the image processor; the third resistor is coupled in series with the fourth resistor and coupled between the second supply voltage and ground, the third resistor and a connecting end of the fourth resistor is coupled to an anode end of the second diode, a cathode end of the second diode, a cathode end of the first diode, an end of the fifth resistor, and the One end of the first capacitor is coupled to the analog digital input of the image processor, and the fifth resistor and the first capacitor are filtered to remove high frequency noise coupled into the line. Preventing high-frequency noise with high potential from entering the analog digital conversion input end of the image processor, and the resistance value of the fifth resistor is much larger than the resistance value of the first resistor to the fourth resistor to avoid affecting the first A sampling of the supply voltage and the second supply voltage.

The functions of the display system and the voltage protection device of the present invention are:

1. The overvoltage protection device uses the control module to compare the detection value of the sampling module output detection voltage with the built-in reference value, and is not affected under high temperature and high humidity conditions, so no malfunction occurs.

2. The sampling module of the overvoltage protection device samples the first supply voltage and the second supply voltage to obtain a detection voltage as a detection value, and then uses the control module to perform the detection value and the built-in reference value. Comparison makes the overall overvoltage judgment reference more accurate.

3. The overvoltage protection device uses the control module to set the reference value, making the voltage protection control process easier.

The foregoing and other technical features, features, and advantages of the present invention will be apparent from the following detailed description of the preferred embodiments Now.

Referring to FIG. 3, in a preferred embodiment of the present invention, the display system 100 includes a power conversion module 3, a panel peripheral circuit 4, a backlight module 5, an energy saving control circuit 2, and an overvoltage protection device 1.

The power conversion module 3 includes an EMI filter circuit 311, a bridge rectifier circuit 312, a PFC circuit 313, a main power conversion circuit 314, and a standby power conversion circuit 316. The EMI filter circuit 311 receives AC power (eg, 90-264 Vac). The input of the signal is used to filter out the conductive electromagnetic interference, the bridge rectifier circuit 312 performs full-wave rectification, the PFC circuit 313 corrects the current waveform and the filtered bus voltage Vbus (for example, about 400V).

The main power conversion circuit 314 receives the bus voltage Vbus and performs step-down conversion to output a first supply voltage Vm1 (eg, 24V) and a second supply voltage Vm2 (eg, 12V), wherein the first supply voltage Vm1 is supplied to the backlight module 5 The operating voltage, and the second supply voltage Vm2 provides the operating voltage of the peripheral circuit 4 of the panel, such as a liquid crystal panel driver circuit (Panel Driver Circuit) and an audio circuit (Audio Circuit).

The standby power conversion circuit 316 receives the bus voltage Vbus and performs step-down conversion to output a third supply voltage, and outputs an auxiliary voltage Vaux. The third supply voltage of the embodiment is a standby voltage Vsb, which is in the standby power conversion circuit 316. The auxiliary winding voltage of the transformer is rectified and filtered to generate an auxiliary power supply voltage Vaux (such as 12-19V), and the standby voltage Vsb (for example, 5V) is required to supply energy to the energy-saving control circuit 2 and other internal components of the circuit.

The peripheral circuit 4 of the panel is electrically connected to the power conversion module 3, and is driven by the second power supply voltage Vm2 to operate normally; the backlight module 5 is electrically connected to the power supply. The module 3 is driven by the first power supply voltage Vm1 to operate normally; the energy-saving control circuit 2 is electrically connected to the power conversion module 3, receives the auxiliary voltage Vaux and the standby voltage Vsb, and is converted into the PFC circuit 313 in the power conversion module 3. The controller 330 and the controller 340 of the main power conversion circuit 314 require a supply voltage Vcc, and can be disabled by the overvoltage protection device 1 or enable the supply voltage Vcc to be output to the power conversion module 3. The controller 330 of the PFC circuit 313 and the controller 340 of the main power conversion circuit 314.

The overvoltage protection device 1 is electrically connected to the power conversion module 3, and includes a control module 11 and a sampling module 12; the sampling module 12 receives the first power supply voltage Vm1 and the second power supply output by the power conversion module 3 voltage Vm2, and the first supply voltage Vm1 and Vm2 performed by the second supply voltage dividing resistors R1, R2 and R3, R4 after a detection voltage output sampling ratio V _OVP.

Referring to FIG. 3 and FIG. 4, the control module 11 is an image processor 110 of the motherboard control circuit. The image processor 110 integrates a microcontroller (MCU: Micro Control Unit). The measured voltage V _OVP analog/digital is converted into a detected value, and the detected value is compared with a built-in reference value. If it is determined that the detected value is not greater than the reference value, the high-level control voltage V is output. _{PS_ON} controls the energy-saving control circuit 2 to enable the supply voltage Vcc output, so that the controller 330 of the PFC circuit 313 of the power conversion module and the controller 340 of the main power conversion circuit 314 are in the "operation mode"; if the detection value is greater than the reference For the value, the low-level control voltage V _{PS_ON} is output to control the energy-saving control circuit 2 to disable the supply voltage Vcc output, so that the controller 330 of the PFC circuit 313 of the power conversion module and the controller 340 of the main power conversion circuit 314 are in the "" The sleep mode, that is, when the first power supply voltage Vm1 or the second power supply voltage Vm2 outputted by the power conversion module 3 is overvoltage, the main power conversion circuit 314 in the power conversion module 3 is turned off.

Referring to FIG. 4, the internal components of the energy-saving control circuit 2 are similar to those of the energy-saving control circuit 97 of FIG. 2, and the functions of the components can also be referred to the description of FIG. 2, except that the circuit of FIG. 4 is omitted. Diode D1 of 2 and output OVP.

The detailed principle of the overvoltage protection device 1 is as follows: the sampling module 12 has a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, and a fifth resistor R5. a first diode D1, a second diode D2, and a first capacitor C1. The first resistor R1 is coupled in series with the second resistor R2 and coupled between the first supply voltage Vm1 and the ground, and the connection end of the first resistor R1 and the second resistor R2 is coupled to the first diode D1. The anode end of the first diode D1 is coupled to the analog-to-digital conversion (ADC) input of the image processor 110; the third resistor R3 is coupled in series with the fourth resistor R4 and coupled to the second power supply. Between the voltage Vm2 and the ground, the connection end of the third resistor R3 and the fourth resistor R4 is coupled to the anode end of the second diode D2, the cathode end of the second diode D2, and the first diode D1 The cathode terminal, one end of the fifth resistor R5, and one end of the first capacitor C1 are coupled to each other, and are also coupled to the analog digital conversion input terminal of the image processor 110, and the first power supply voltage Vm1 can be obtained by the above component. After the scaling is performed by the resistors R1 and R2, the first sampling voltage Vm1"=Vm1 ^* R2/(R1+R2) and the second power supply voltage Vm2 are scaled down by the resistors R3 and R4 to obtain the second sampling voltage Vm2"=Vm2. ^{* R4 / (R3 + R4)} , a first sampled voltage Vm1 "and the second sampling voltage Vm2" that a high voltage, eg: a first supply When the voltage of the voltage Vm1 is normal and the voltage of the second supply voltage Vm2 is abnormally increased, the voltage of the second sampling voltage Vm2" is greater than the voltage of the first sampling voltage Vm1", and the voltage of the second sampling voltage Vm2" is output to the image processor 110 through the diode D2. Analog to digital conversion input.

The RC filter circuit composed of the fifth resistor R5 and the first capacitor C1 is used for filtering high frequency noise coupled into the line to prevent the high frequency noise of the higher potential from entering the analog digital input of the image processor 110. The terminal is misjudged as an overvoltage protection signal; the resistance value of the fifth resistor R5 is much larger than the resistance values of the first to fourth resistors R1 to R4 to avoid affecting the first supply voltage Vm1 and the second supply voltage Vm2 Sampling.

Referring to FIG. 5, the image processor 110 has a built-in program for determining the detected value of the DC voltage analog digital conversion. The flow includes the following steps: determining that the detected value is greater than the reference value (step 501)? If not, it means that the overvoltage protection is not required, that is, the power supply voltage Vcc is output to the power conversion module 3 (step 502), and the operation mode is entered (step 504); if the detection value is greater than the reference value, it represents Overvoltage protection is required, that is, the supply voltage Vcc is disabled from being output to the power conversion module 3 (step 503), and is put into the sleep mode (step 505).

In this embodiment, if the first supply voltage Vm1 does not exceed the first overvoltage protection value of (Vref+Vf1)×(R1+R2)/R2, and the second supply voltage Vm2 does not exceed (Vref+Vf2)×( The second overvoltage protection value of R3+R4)/R4 indicates that the detected detection voltage V _{OVP is} less than the internally set reference voltage Vref, and the signal port PS_ON output is originally a high high (High) signal to make the power conversion Module 3 enters the working mode for normal operation.

If the first supply voltage Vm1 exceeds the first overvoltage protection value of (Vref+Vf1)×(R1+R2)/R2, or the second supply voltage Vm2 exceeds (Vref+Vf2)×(R3+R4)/R4 When the second overvoltage protection value indicates that the detected detection voltage V _{OVP is} greater than the internally set reference voltage Vref, the signal port PS_ON will output a continuous low (Low) signal to cause the power conversion module 3 to enter the sleep mode to stop, That is, when the first power supply voltage Vm1 or the second power supply voltage Vm2 outputted by the power conversion module 3 is overvoltage, the main power conversion circuit 314 in the power conversion module 3 is turned off.

In summary, the functions of the display system 100 and the overvoltage protection device 1 of the present invention are as follows:

1. The overvoltage protection device 1 compares the first supply voltage Vm1 and the second supply voltage Vm2 output by the sampling power conversion module according to the control module 11 to obtain a detection value compared with the built-in reference value, at a high temperature It will not be affected under wet conditions, so it will not cause malfunction.

2. The sampling module 12 of the overvoltage protection device 1 samples the first supply voltage Vm1 and the second supply voltage Vm2 outputted by the power conversion module 3, and outputs a detection value, and then the detection value is controlled by the control module 11. Compared with the built-in reference value, the overall overvoltage judgment reference is more accurate.

3. The overvoltage protection device 1 uses the control module 11 to set a reference value to make the voltage protection control process easier, so that the object of the present invention can be achieved.

However, the above is only the preferred embodiment of the present invention, and the scope of the present invention cannot be limited thereto, that is, the scope of patent application according to the present invention. And the simple equivalent changes and modifications made by the description of the invention are still within the scope of the invention.

[study]

90‧‧‧Motherboard control circuit

91‧‧‧Power conversion device

911‧‧‧EMI filter circuit

912‧‧‧Bridge rectifier circuit

913‧‧‧PFC circuit

914‧‧‧Main power conversion circuit

916‧‧‧Standby power conversion circuit

930, 940‧‧ ‧ controller

92‧‧‧Panel peripheral circuits

93‧‧‧Backlight module

931‧‧‧LED drive circuit

932‧‧‧LED light source

97‧‧‧Energy-saving control circuit

98‧‧‧Overvoltage protection circuit

〔this invention〕

100‧‧‧Display system

1‧‧‧Overvoltage protection device

11‧‧‧Control module

12‧‧‧Sampling module

110‧‧‧Image Processor

2‧‧‧Energy saving control circuit

3‧‧‧Power conversion device

311‧‧‧EMI filter circuit

312‧‧‧Bridge rectifier circuit

313‧‧‧PFC circuit

314‧‧‧Main power conversion circuit

316‧‧‧Standby power conversion circuit

330, 340‧‧‧ controller

4‧‧‧Panel peripheral circuits

5‧‧‧Backlight module

501~505‧‧‧Steps

1 is a system block diagram illustrating an internal module of a conventional liquid crystal display system; and FIG. 2 is a circuit diagram illustrating components of an energy saving control circuit, an overvoltage protection circuit, and a host control circuit of the conventional liquid crystal display system; A system block diagram illustrating an internal module of a display system in a preferred embodiment of the present invention; FIG. 4 is a circuit diagram illustrating an overvoltage protection device and an energy saving control circuit of the liquid crystal display system of the present invention; and FIG. 5 is a flow chart The figure illustrates the steps of determining and processing the detected value of the DC voltage analog-to-digital conversion by the built-in program of the liquid crystal display system of the present invention.

100‧‧‧Display system

1‧‧‧Overvoltage protection device

11‧‧‧Control module

12‧‧‧Sampling module

2‧‧‧Energy saving control circuit

3‧‧‧Power conversion device

311‧‧‧EMI filter circuit

312‧‧‧Bridge rectifier circuit

313‧‧‧PFC circuit

314‧‧‧Main power conversion circuit

316‧‧‧Standby power conversion circuit

330, 340‧‧‧ controller

4‧‧‧Panel peripheral circuits

5‧‧‧Backlight module

Claims (8)

An overvoltage protection device for a display system, the display system having a power conversion module, a panel peripheral circuit, a backlight module and an energy saving control circuit, wherein the energy saving control circuit is controlled by the overvoltage protection device to output a power supply voltage The overvoltage protection device includes: a sampling module electrically connected to the power conversion module, receiving a first power supply voltage outputted by the power conversion module to the backlight module, and receiving the power conversion module output to the a second supply voltage of the peripheral circuit of the panel, and the first supply voltage and the second supply voltage are separately scaled and sampled, and then output a higher voltage after sampling as a detection voltage; and a control The module is electrically connected to the sampling module and the energy-saving control circuit, and converts the detected voltage analog/digital digit outputted by the sampling module into a detected value, and compares the detected value with a built-in reference value. If it is determined that the detected value is not greater than the reference value, controlling the energy-saving control circuit to enable the power supply voltage output, so that the power conversion module is in an operating mode; The detection value is greater than the reference value, and the energy-saving control circuit is controlled to disable the power supply voltage output, so that the power conversion module is in a sleep mode. The overvoltage protection device of the display system according to claim 1, wherein the control module controls the energy-saving control circuit to output the power supply voltage to a controller or a main power source of a PFC circuit of the power conversion module. The controller of the conversion circuit. The overvoltage protection device of the display system according to claim 2, wherein the control module is an image processor of the mainboard control circuit. Overvoltage protection device for display system according to item 3 of the patent application scope The sampling module has a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a first diode, and a second a first capacitor and a first capacitor; the first resistor is coupled in series with the second resistor and coupled between the first supply voltage and the ground, and the connection end of the first resistor and the second resistor is coupled to the An anode end of the first diode, the cathode end of the first diode is coupled to an analog digital conversion input of the image processor; the third resistor is coupled in series with the fourth resistor and coupled to the Between the second supply voltage and the ground, the connection end of the third resistor and the fourth resistor is coupled to the anode end of the second diode, the cathode end of the second diode, the first two a cathode end of the pole body, an end of the fifth resistor, and one end of the first capacitor are coupled to each other and coupled to an analog digital conversion input end of the image processor; wherein the fifth resistor and the first The capacitor filters out high frequency noise coupled into the line to prevent high frequency noise from entering the image processing. The analog to digital conversion input terminal, and the resistance value of the fifth resistor is greater than the resistance value of the first resistor to the fourth resistor to avoid the effects of sampling to the first power supply voltage and the second supply voltage. A display system includes: a power conversion module that converts a mains power into a first power supply voltage, a second power supply voltage, and a third power supply voltage, and is driven by a power supply voltage; a backlight module Electrically connecting the power conversion module to receive the first power supply voltage for normal operation; a peripheral circuit of the panel is electrically connected to the power conversion module, and is driven by the second power supply voltage to operate normally; An energy-saving control circuit electrically connecting the power conversion module, receiving the third power supply voltage and converting the power supply voltage required by the power conversion module, and being disabled or enabled by the overvoltage protection device The power supply voltage is output to the power conversion module; and an overvoltage protection device is electrically connected to the power conversion module, comprising: a sampling module, receiving the first power supply voltage and the second output by the power conversion module a power supply voltage, and the first power supply voltage and the second power supply voltage are respectively scaled down and sampled, and the higher voltage is output as a detection voltage, and a control module is used to detect the voltage The voltage analog/digital conversion is converted into a detection value, and the detection value is compared with a built-in reference value. If it is determined that the detection value is not greater than the reference value, the energy-saving control circuit is controlled to enable the supply voltage output. The power conversion module is in an active mode; if it is determined that the detection value is greater than the reference value, the energy-saving control circuit is controlled to disable the power supply voltage output, so that the power conversion module is in a sleep mode. The display system according to claim 5, wherein the power conversion module has a controller of a PFC circuit and a controller of a main power conversion circuit, a controller of the PFC circuit and the main power conversion circuit The controller is controlled by the supply voltage in the active mode or the sleep mode. The display system according to claim 6, wherein the control module is an image processor of the mainboard control circuit. The display system of claim 7, wherein the sampling module has a first resistor, a second resistor, a third resistor, and a first a fourth resistor, a fifth resistor, a first diode, a second diode, and a first capacitor; the first resistor is coupled in series with the second resistor and coupled to the first supply voltage and ground The connection between the first resistor and the second resistor is coupled to the anode end of the first diode, and the cathode end of the first diode is coupled to the analog digital of the image processor. a conversion input terminal; the third resistor is coupled in series with the fourth resistor and coupled between the second supply voltage and the ground, and the connection end of the third resistor and the fourth resistor is coupled to the second An anode end of the diode, a cathode end of the second diode, a cathode end of the first diode, an end of the fifth resistor, and one end of the first capacitor are coupled to each other An analog digital conversion input end of the image processor; wherein the fifth resistor and the first capacitor filter out high frequency noise coupled into the line to prevent high frequency high frequency noise from entering the image processing The analog-to-digital conversion input of the device, and the resistance value of the fifth resistor is much larger than the first resistor to the fourth The resistance value is to avoid affecting the sampled first power supply voltage and the second supply voltage.