CN201374641Y - Anti-electromagnetic interference circuit structure of large-screen liquid crystal television - Google Patents
Anti-electromagnetic interference circuit structure of large-screen liquid crystal television Download PDFInfo
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- CN201374641Y CN201374641Y CN200820180762U CN200820180762U CN201374641Y CN 201374641 Y CN201374641 Y CN 201374641Y CN 200820180762 U CN200820180762 U CN 200820180762U CN 200820180762 U CN200820180762 U CN 200820180762U CN 201374641 Y CN201374641 Y CN 201374641Y
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- 239000004973 liquid crystal related substance Substances 0.000 title claims abstract description 12
- 238000001914 filtration Methods 0.000 claims description 8
- 230000002401 inhibitory effect Effects 0.000 abstract 1
- 238000000034 method Methods 0.000 description 4
- 238000006243 chemical reaction Methods 0.000 description 3
- 230000005540 biological transmission Effects 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000033228 biological regulation Effects 0.000 description 1
- 239000003990 capacitor Substances 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000008030 elimination Effects 0.000 description 1
- 238000003379 elimination reaction Methods 0.000 description 1
- 238000004146 energy storage Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000001939 inductive effect Effects 0.000 description 1
- 230000005764 inhibitory process Effects 0.000 description 1
- 230000001151 other effect Effects 0.000 description 1
- 230000005855 radiation Effects 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 230000009466 transformation Effects 0.000 description 1
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Abstract
The utility model relates to an anti-electromagnetic interference circuit structure of a large-screen liquid crystal television, which belongs to the field of televisions. The anti-electromagnetic interference circuit structure comprises a power module connected with a circuit mainboard, and the connection relation at the inlet of the power module of the prior circuit is changed, that is, an anti-electromagnetic interference filter module which consists of a low pass filter for inhibiting common-mode interference signals, is added. The utility model can effectively inhibit common-mode interference signals in the power circuit, so that a switch power supply can stably operate, and thereby the large-screen liquid crystal television can have a stable working environment.
Description
Technical field
The utility model belongs to the television equipment field, specially refers to the circuit structure of the anti-electromagnetic interference of a kind of large-screen liquid crystal display television.
Background technology
Along with the Electro Magnetic Compatibility of electronic product comes into one's own day by day, suppress the electromagnetic interference of Switching Power Supply, improve the quality of electronic product, make it to meet relevant electromagnetic compatibility standard or standard, become the problem that design of electronic products person more and more pays close attention to.Because the LCD TV of screen sizes is very universal, the electromagnetic interference (EMI) filtering technique is comparative maturity also, puts before this and analyzes the liquid crystal television circuit, and overcoming electromagnetic interference problem just has comparatively firm basis.Present most LCD TV all is to adopt Switching Power Supply because power is big, general conduction test be very difficult to by, built-in power supply is because design reasons sometimes can not effectively suppress the electromagnetic interference of power supply, the just measure that must suppress specially.
The reason of Switching Power Supply generation electromagnetic interference is more, and wherein the peak voltage that the electric current high order harmonic component is disturbed and the transformer type circuit for power conversion the produces interference that is produced by basic rectifier is a main cause.The switching process of basic rectifier is to produce the modal reason of electromagnetic interference.This is that this current wave can be decomposed into the DC component alternating current component sum different with a series of frequencies because sine-wave power becomes the electric current that unidirectional pulsafeeder no longer is a single-frequency after by rectifier.Experimental result shows that harmonic wave (particularly high order harmonic component) can produce conducted interference and radiated interference along transmission line, on the one hand the current waveform that is connected on its front end power line is distorted, and produces radio frequency interference by power line on the other hand.The transformer type circuit for power conversion is the core of switching power supply in order to realize transformation, frequency conversion and to finish the output voltage adjustment, mainly is made up of switching tube and high frequency transformer.The peak voltage that it produces is a kind of burst pulse that has by a relatively large margin, and its frequency band broad and harmonic ratio are abundanter.The main cause that produces this impulse disturbances is: (1) power switch transistor inductive load be high frequency transformer or energy storage inductor in the moment of switching tube conducting, very big shoving appears in primary, will cause spike noise.This spike noise is actually spike, and the lighter causes interference, and weight person might the breakdown switch pipe.(2) interference that is produced by high frequency transformer is when the switching tube shutoff of original conducting, (wherein E is an electromotive force to the back-emf E=-Ldi/dt that leakage inductance produced of transformer,) its value is directly proportional with the current changing rate (di/dt) of collector electrode, be directly proportional with the leakage inductance amount, be superimposed upon on the shutoff voltage, form the shutoff voltage spike, form the conductibility electromagnetic interference, both influenced the elementary of transformer, and also can conduct, influenced the safety and the economical operation of other power consumption equipment to distribution system.(3) interference that produces by the output rectifier diode the output rectifier diode by the time, a reverse current is arranged, factors such as the time that it returns to zero point and junction capacitance are relevant.Wherein reverse current can be returned to the diode at zero point rapidly and be called hard recovery characteristics diode, this diode will produce stronger High-frequency Interference under transformer leakage inductance and other effects of distribution parameters, and its frequency can reach tens megahertzes.
Summary of the invention
The utility model technical issues that need to address, be that the Switching Power Supply that adopts at present most of LCD TV all produces stronger high-frequency electromagnetic interference, especially just more outstanding at the LCD TV electromagnetic interference problem of large-screen, influence the Switching Power Supply performance, thereby influence the LCD TV performance, in order to overcome this drawback, will develop a kind of anti-disturbance method, suppress to appear at the electromagnetic interference in the LCD TV, the purpose of this utility model provides the circuit structure of the anti-electromagnetic interference of a kind of large-screen liquid crystal display television, for realizing the purpose of this utility model, the technical scheme that is adopted is as follows: the circuit structure of the anti-electromagnetic interference of a kind of large-screen liquid crystal display television, comprise the power module that is connected with circuit main board, it is characterized in that, change its annexation in the porch of original circuit power module, increase the filtration module of an anti-electromagnetic interference, described filtration module comprises the low pass filter that suppresses common mode interference signal.
The theoretical foundation of the technical program is as follows: reach to the power supply common mode inhibition of differential mode interference etc. by Electromagnetic interference filter.Conducted interference signal on any power source line, all available differential mode and common-mode signal are represented.Differential mode interference is transmitted between two leads, belongs to symmetry and disturbs; Common mode disturbances transmission between lead and ground (casing) belongs to asymmetry and disturbs.In the ordinary course of things, the differential mode interference amplitude is little, frequency is low, interference that caused is less; The common mode disturbances amplitude is big, frequency is high, can also produce radiation by lead, and the interference that is caused is bigger.Therefore, desire weakens conducted interference, electromagnetic interference signal is controlled at below the limiting level of relevant electromagnetic compatibility standard regulation, and effective method installs Electromagnetic interference filter additional exactly in Switching Power Supply input and output circuit.The operating frequency of Switching Power Supply is about 10kHz～100kHz.The limiting value of the conducted interference level of a lot of standard codes of electromagnetic compatibility all is to count from 10kHz.High band electromagnetic interference signal to Switching Power Supply produces as long as select the comparatively simple Electromagnetic interference filter of suitable decoupling circuit or network configuration, just can obtain satisfied effect
Very big of the power of some large-screen liquid crystal display televisions, have in addition can reach 500W, the interference of power supply can't be effectively restrained in general power supply design, so we have increased the filtration module of an electromagnetic interference in the porch of power supply.The beneficial effects of the utility model are can restrain common mode interference signal effectively in power circuit, make the Switching Power Supply steady operation, thereby make large-screen liquid crystal display television that a stable operational environment be arranged.
Description of drawings
Fig. 1 connects calcspar for the power circuit that the utility model adopts;
Fig. 2 is the emi-filter module circuit structure diagram in the circuit.
Embodiment
With reference to Fig. 1, the power circuit that adopts for the utility model connects calcspar, and wherein power module 1 connects EMI filtration module 2 and TV SKD 3, and EMI filtration module 2 connects mains supply again.
With reference to Fig. 2, be the emi-filter module circuit structure diagram in the circuit, wherein A is a live wire, and N is a zero line, and G is a ground wire.Cc1, Cc2 and LC1, LC2 constitute first low pass filter 2-1, and it is used to suppress common mode interference signal.Because the frequency of power supply interference signal is much larger than power frequency 50Hz, so they disturb by capacitor C c1, Cc2 access ground elimination.LC1, LC2 are the magnetic core inductance, and it is compared with common inductance has the advantages that volume is little, inductance value is big, is called common mode inductance in this circuit, LC1, and the equal turn numbers of two groups of coils of LC2 is around on the contrary.The polarity of common mode interference signal is identical, and at LC1, LC2 produces very big impedance, enters follow-up rectification circuit thereby suppress common-mode signal.Opposite for polarity, be serially connected in the differential mode interference signal in the power supply, LC1, the impedance that LC2 produces is zero, then forms second low pass filter 2-2 by Cd1, Ld and suppresses interference signal.
Claims (2)
1. the circuit structure of the anti-electromagnetic interference of large-screen liquid crystal display television, comprise the power module that is connected with circuit main board, it is characterized in that, change its annexation in the porch of original circuit power module, increase the filtration module of an anti-electromagnetic interference, described filtration module comprises the low pass filter that suppresses common mode interference signal.
2. the circuit structure of the anti-electromagnetic interference of large-screen liquid crystal display television according to claim 1, it is characterized in that, described low pass filter, comprise two parts, they are by Cc1, Cc2 and LC1, and LC2 constitutes first low pass filter (2-1) and constitutes second low pass filter (2-2) by Cd1, Ld and forms.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN200820180762U CN201374641Y (en) | 2008-12-08 | 2008-12-08 | Anti-electromagnetic interference circuit structure of large-screen liquid crystal television |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN200820180762U CN201374641Y (en) | 2008-12-08 | 2008-12-08 | Anti-electromagnetic interference circuit structure of large-screen liquid crystal television |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN201374641Y true CN201374641Y (en) | 2009-12-30 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN200820180762U Expired - Fee Related CN201374641Y (en) | 2008-12-08 | 2008-12-08 | Anti-electromagnetic interference circuit structure of large-screen liquid crystal television |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109036317A (en) * | 2018-09-10 | 2018-12-18 | 惠科股份有限公司 | Display device and driving method |
| CN111413818A (en) * | 2020-03-31 | 2020-07-14 | 精电(河源)显示技术有限公司 | Liquid crystal display module capable of resisting electrical interference |
-
2008
- 2008-12-08 CN CN200820180762U patent/CN201374641Y/en not_active Expired - Fee Related
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109036317A (en) * | 2018-09-10 | 2018-12-18 | 惠科股份有限公司 | Display device and driving method |
| US11295692B2 (en) | 2018-09-10 | 2022-04-05 | HKC Corporation Limited | Display device and driving method |
| CN111413818A (en) * | 2020-03-31 | 2020-07-14 | 精电(河源)显示技术有限公司 | Liquid crystal display module capable of resisting electrical interference |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| C17 | Cessation of patent right | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20091230 Termination date: 20111208 |