CN201045695Y - Signal processing circuit for VGA interface and television set equipped with the same - Google Patents
Signal processing circuit for VGA interface and television set equipped with the same Download PDFInfo
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- CN201045695Y CN201045695Y CNU2007200189822U CN200720018982U CN201045695Y CN 201045695 Y CN201045695 Y CN 201045695Y CN U2007200189822 U CNU2007200189822 U CN U2007200189822U CN 200720018982 U CN200720018982 U CN 200720018982U CN 201045695 Y CN201045695 Y CN 201045695Y
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Abstract
The utility model discloses a signal processing circuit for a VGA port and a TV set with the circuit. Imitate RGB signal, synchronous signal, and bus signal which are input through the VGA port are ESD- protected, and are wave-shaped, and are bus electrical level switch processed through a positive-negative voltage embedded position, a schmitt trigger, and bus signal, and the imitate RGB signal, synchronous signal, and bus signal are output to an audio processing circuit. The electrostatic protection function of the VGA port is realized by a simple circuit structure and the lower cost, thereby damage to the audio display equipment caused by high-pressure interference which is interfused in the signal source is effectively avoided, wave shape of the synchronous signal is improved, the problem of wave shape infidelity caused during the transmitting process of the signal is eliminated, and matching require of the VGA port with DDC bus electric level among different audio processing chip is satisfied simultaneously.
Description
Technical field
The utility model belongs to the signal processing technology field, specifically, relates to a kind of VGA Signal Processing circuit.
Background technology
Present televisor all is provided with the VGA interface usually, can external VGA signal source equipment.VGA is the abbreviation of English Video Graphics Array, is exactly the interface of output simulating signal on the video card, also is the D-Sub interface.Though LCD is receiving digital signals directly,, a lot of low-end products be in order to be complementary with VGA interface video card, thereby also are provided with the VGA interface.
For the on-board liquid crystal television machine that disposes the VGA interface at present, because its applied environment is abominable, the high-pressure electrostatic that signal source produces is easy to destroy the internal circuit of on-board liquid crystal television, cause the damage of in-car TV, thereby the configuration electrostatic discharge protection circuit is very important on the VGA of on-board liquid crystal television interface.
In addition; for different VGA signal sources; on its synchronizing signal, exist undesired signal through regular meeting; and the quality of synchronizing signal is often determining the success or failure of whole VGA signal Processing; unpurified synchronizing signal causes the unusual of complete machine image demonstration through regular meeting; thereby had a strong impact on user's visual effect, reduced the complete machine quality of tv product.
In addition, because the DDC bus signals in the VGA interface is a Transistor-Transistor Logic level, and some video frequency processing chips adopts at present is the DDC bus of CMOS level, and the bus of these two kinds of varying levels can not directly couple together, and need set up level shifting circuit and assist realization.
Therefore, how finishing above-mentioned three tasks by simple circuit configuration is subject matter to be solved in the utility model.
The utility model content
Goal of the invention of the present utility model is to provide a kind of signal processing circuit of the VGA of being used for interface, to realize the shaping processing to the VGA signal waveform.
At first, for the high-pressure electrostatic of sneaking in effective filtering VGA signal disturbs, suffer damage with the electric equipment internal circuit of avoiding disposing the VGA interface; In the utility model, this signal processing circuit comprises the VGA interface, clamped module of generating positive and negative voltage and video processing circuits, the analog rgb signal that described VGA interface receives output to video processing circuits after carrying out the electrostatic defending processing by the clamped module of generating positive and negative voltage.
Secondly, in order to improve the waveform of synchronizing signal in the VGA signal, avoiding its distortion, thereby influence the image output quality of video display apparatus; In the utility model, described signal processing circuit also comprises a pair of Schmidt trigger, line synchronizing signal that described VGA interface receives and field sync signal output to described video processing circuits after carrying out the wave shaping processing by No. one Schmidt trigger separately.
At last, in order to mate the bus level state between VGA interface and the video frequency processing chip, to satisfy the reliable transmission of bus data; In the utility model, described signal processing circuit also comprises level shifting circuit, the Transistor-Transistor Logic level bus signals that described VGA interface receives carries out Transistor-Transistor Logic level after the conversion process between the CMOS level by this level shifting circuit, outputs to described video processing circuits.
Described signal processing circuit comprises that also is used to control the conversion control circuit whether described level shifting circuit works.Wherein, described conversion control circuit is a direct current power supply.
The utility model provides a kind of televisor of the VGA of having interface signal treatment circuit simultaneously again, this televisor comprises the VGA interface, clamped module of generating positive and negative voltage and video processing circuits, the analog rgb signal that described VGA interface receives outputs to video processing circuits after carrying out the electrostatic defending processing by the clamped module of generating positive and negative voltage.
Further, also comprise a pair of Schmidt trigger in described televisor, line synchronizing signal that described VGA interface receives and field sync signal output to described video processing circuits after carrying out the wave shaping processing by No. one Schmidt trigger separately.
Further again, in described televisor, also comprise level shifting circuit, the Transistor-Transistor Logic level bus signals that described VGA interface receives carries out Transistor-Transistor Logic level after the conversion process between the CMOS level by this level shifting circuit, outputs to described video processing circuits.
Further again, comprise also that in described televisor is used to control the conversion control circuit whether described level shifting circuit works.Wherein, described conversion control circuit can adopt a direct current power supply to realize.
Compared with prior art, advantage of the present utility model and good effect are: the utility model is by being provided with the clamped module of generating positive and negative voltage, Schmidt trigger and level shifting circuit between the VGA of electric equipment interface and video processing circuits, not only realized the electrostatic defending effect of VGA interface, the high pressure of effectively having avoided sneaking in the signal source disturbs the damage that video display apparatus is caused, and has solved the problem that the in-car TV machine is in use easily broken by static.Simultaneously, also realized the shaping of synchronization waveform in the VGA signal is handled, eliminated the waveform distortion problem that causes in the signals transmission; And satisfied the DDC bus level coupling requirement between VGA interface and the different video process chip.
Description of drawings
Fig. 1 is the schematic diagram that is used for the signal processing circuit of VGA interface in the utility model.
Embodiment
Below in conjunction with the drawings and specific embodiments the utility model is done explanation in further detail.
The VGA interface is a kind of D type interface, has 15 pin holes above, is divided into three rows, five of every rows.The VGA interface is the interface type that is most widely used on the video card, and most video cards all have this kind interface.All be to be connected between most computers and the external display device at present by simulation VGA interface, the displays image information that computer-internal generates with digital form, changed into R, G, B tricolor signal and row, field sync signal by the digital/analog converter in the video card, signal by cable transmission in display device.For analog display device, as the simulation CRT monitor, signal is directly delivered to corresponding treatment circuit, and the drive controlling kinescope generates image.And, need the corresponding A/D converter of configuration in the display device for digital distance scopes such as LCD, DLP, be digital signal with analog-signal transitions.After through D/A and twice conversion of A/D, caused the loss of some image details inevitably.The VGA Application of Interface is given no cause for much criticism in CRT monitor, but is used to connect the display device of liquid crystal and so on, and then the image impairment of transfer process can make display effect descend slightly.But,,,, also be provided with the VGA interface usually in order to be complementary with VGA interface video card as on-board liquid crystal television machine etc. for a lot of low-end products.
Embodiment one, because on-board liquid crystal television machine working environment is more abominable, the signal of importing by the VGA interface is easy to be interfered in transmission course, causes the decline of image output quality.For head it off, the utility model is provided with signal processing circuit between the VGA of electric equipment interface and video processing circuits, and this signal processing circuit comprises the clamped module of generating positive and negative voltage, Schmidt trigger and level shifting circuit three parts.Wherein, simulation RED, the GREEN that the VGA interface receives, BLUE signal output to video processing circuits after carrying out the electrostatic defending processing by the clamped module of generating positive and negative voltage; Line synchronizing signal that the VGA interface receives and field sync signal output to described video processing circuits after carrying out the wave shaping processing by No. one Schmidt trigger separately; The Transistor-Transistor Logic level bus signals that the VGA interface receives then carries out Transistor-Transistor Logic level after the conversion process between the CMOS level by level shifting circuit, outputs in the described video processing circuits.
Described signal processing circuit comprises that also is used to control the conversion control circuit whether described level shifting circuit works.Wherein, described conversion control circuit is a direct current power supply, realizes described level shifting circuit work whether selection control by the magnitude of voltage that direct supply is set.
Embodiment two, and in order to simplify circuit structure, the utility model can adopt the interface chip CM2006 of a high integration to be connected between described VGA interface and the video processing circuits, forms described signal processing circuit.Wherein, in the interface chip CM2006 of described high integration, be built-in with the clamped module of described generating positive and negative voltage, Schmidt trigger and level shifting circuit.
Described interface chip CM2006 is complete VGA and the DVI-I port support circuit that the first item in the industry of Micro Equipment Co. of Galifornia's release is used for Digital Television and LCD display.CM2006 has substituted 22 simulations and passive element, integrated esd protection, level conversion and buffering three partial functions in a single-chip.
As shown in Figure 1, XS7 is the VGA interface of 15 pin holes, from simulation RED, the GREEN of 1,2,3 pin of VGA interface XS7 input, the electrostatic defending end 3,4,5 that the BLUE signal is connected to chip CM2006 earlier, after voltage clamping circuit by described chip CM2006 inside carries out the clamped processing of generating positive and negative voltage to the analog rgb signal, connect video processing circuits by 4,5 pin 3, equally.From being higher than of VGA interface XS7 input+5.5V or be lower than-electrostatic pulse of 0.5V will be released on chip CM2006.Because normal RED, GREEN, BLUE signal because amplitude within-0.5V-+5.5V, so this chip CM2006 is to normal RED, GREEN, not influence of BLUE signal transmission.
15,13 pin that enter chip CM2006 from the line synchronizing signal VGAHS and the field sync signal VGAVS of 13,14 pin of VGA interface XS7 input, after carrying out wave shaping and handle by the built-in schmitt trigger of chip CM2006, line synchronizing signal AHS after being handled by 16, the 14 pin output of chip CM2006 again and field sync signal AVS are to video frequency processing chip, by wave shaping to synchronizing signal, but the synchronization waveform distortion that causes in the erasure signal transmission course.
Be connected to 12,9 pin of chip CM2006 from DDC bus signals DDCSDA, the DDCSCL of 12,15 pin of VGA interface XS7 input, the DDC bus signals ASDA of video frequency processing chip, ASCL signal are connected to 11,10 pin of chip CM2006, and connect direct supply+5V_M by pull-up resistor R050, R051 respectively.DDC bus signals among the VGA interface XS7 is a Transistor-Transistor Logic level, but what some video frequency processing chip adopted at present is the DDC bus of CMOS level, the bus of these two kinds of varying levels can not directly connect, but utilizes the level shifting circuit of chip CM2006 inside to address this problem.Wherein, in described interface chip CM2006, also include conversion and control end 7 pin of level shifting circuit, the external direct current power supply of described conversion and control end 7 pin; Whether needs carry out specifically determining from Transistor-Transistor Logic level to the conversion the CMOS level magnitude of voltage of described direct supply according to described level shifting circuit.Carry out the level conversion of DDC bus signals if desired,, promptly can realize as long as the conversion and control end 7 pin voltages of chip CM2006 are set to+3.3V.
In the present embodiment, because the DDC bus of video frequency processing chip is a Transistor-Transistor Logic level, do not change so do not need to carry out the level dress, so 7 pin of chip CM2006 can directly connect+5V direct supply+5V_M.
The utility model is handled the VGA signal by the interface chip CM2006 that adopts a high integration, has not only eliminated the electrostatic interference of rgb video signal in the VGA signal, shaping the waveform of capable field sync signal, satisfied the coupling requirement of DDC bus level; And adopt one chip to realize that above-mentioned three tasks have greatly simplified circuit structure, made things convenient for the integral layout of circuit board.
Certainly; above-mentioned explanation is not to be to restriction of the present utility model; the utility model also is not limited in above-mentioned giving an example, and variation, remodeling, interpolation or replacement that those skilled in the art are made in essential scope of the present utility model also should belong to protection domain of the present utility model.
Claims (10)
1. signal processing circuit that is used for the VGA interface, it is characterized in that: this signal processing circuit comprises the VGA interface, clamped module of generating positive and negative voltage and video processing circuits, the analog rgb signal that described VGA interface receives outputs to video processing circuits after carrying out the electrostatic defending processing by the clamped module of generating positive and negative voltage.
2. the signal processing circuit that is used for the VGA interface according to claim 1, it is characterized in that: described signal processing circuit also comprises a pair of Schmidt trigger, line synchronizing signal that described VGA interface receives and field sync signal output to described video processing circuits after carrying out the wave shaping processing by No. one Schmidt trigger separately.
3. the signal processing circuit that is used for the VGA interface according to claim 1 and 2, it is characterized in that: described signal processing circuit also comprises level shifting circuit, the Transistor-Transistor Logic level bus signals that described VGA interface receives carries out Transistor-Transistor Logic level after the conversion process between the CMOS level by this level shifting circuit, outputs to described video processing circuits.
4. the signal processing circuit that is used for the VGA interface according to claim 3 is characterized in that: described signal processing circuit comprises that also is used to control the conversion control circuit whether described level shifting circuit works.
5. the signal processing circuit that is used for the VGA interface according to claim 4 is characterized in that: described conversion control circuit is a direct current power supply.
6. televisor with VGA interface signal treatment circuit, it is characterized in that: this televisor comprises the VGA interface, clamped module of generating positive and negative voltage and video processing circuits, the analog rgb signal that described VGA interface receives outputs to video processing circuits after carrying out the electrostatic defending processing by the clamped module of generating positive and negative voltage.
7. televisor according to claim 6, it is characterized in that: described televisor also comprises a pair of Schmidt trigger, line synchronizing signal that described VGA interface receives and field sync signal output to described video processing circuits after carrying out the wave shaping processing by No. one Schmidt trigger separately.
8. according to claim 6 or 7 described televisors, it is characterized in that: described televisor also comprises level shifting circuit, the Transistor-Transistor Logic level bus signals that described VGA interface receives carries out Transistor-Transistor Logic level after the conversion process between the CMOS level by this level shifting circuit, outputs to described video processing circuits.
9. televisor according to claim 8 is characterized in that: described televisor comprises that also is used to control the conversion control circuit whether described level shifting circuit works.
10. televisor according to claim 9 is characterized in that: described conversion control circuit is a direct current power supply.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNU2007200189822U CN201045695Y (en) | 2007-03-01 | 2007-03-01 | Signal processing circuit for VGA interface and television set equipped with the same |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNU2007200189822U CN201045695Y (en) | 2007-03-01 | 2007-03-01 | Signal processing circuit for VGA interface and television set equipped with the same |
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| Publication Number | Publication Date |
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| CN201045695Y true CN201045695Y (en) | 2008-04-09 |
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| Application Number | Title | Priority Date | Filing Date |
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| CNU2007200189822U Expired - Fee Related CN201045695Y (en) | 2007-03-01 | 2007-03-01 | Signal processing circuit for VGA interface and television set equipped with the same |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101625846B (en) * | 2008-07-08 | 2011-03-30 | 鸿富锦精密工业（深圳）有限公司 | DDC interface circuit |
| CN104424911A (en) * | 2013-08-26 | 2015-03-18 | 英业达科技有限公司 | VGA interface protection circuit |
| CN112272278A (en) * | 2020-12-17 | 2021-01-26 | 天津津航计算技术研究所 | Implementation method for improving VGA video signal transmission performance |
-
2007
- 2007-03-01 CN CNU2007200189822U patent/CN201045695Y/en not_active Expired - Fee Related
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101625846B (en) * | 2008-07-08 | 2011-03-30 | 鸿富锦精密工业（深圳）有限公司 | DDC interface circuit |
| CN104424911A (en) * | 2013-08-26 | 2015-03-18 | 英业达科技有限公司 | VGA interface protection circuit |
| CN104424911B (en) * | 2013-08-26 | 2016-08-31 | 英业达科技有限公司 | Video graphics array (VGA) interface protective circuit |
| CN112272278A (en) * | 2020-12-17 | 2021-01-26 | 天津津航计算技术研究所 | Implementation method for improving VGA video signal transmission performance |
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| Date | Code | Title | Description |
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| 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: 20080409 Termination date: 20110301 |